If the 1970's provide any reasonable prologue, the Washington area's real estate future should be unquestionably upbeat.

However, some significant questions continue to surface as a result of inflationary pressures that triggered unprecedented downtown and suburban commercial building in the 1970s. It is feared that near-runaway borrowing rates and a frenetic pace of commercial construction may produce an era of reckoning and a possible shakedown/shakeout if the general economy turns sour in this decade.

So far, earlier predictions of price collapses in residential real estate have been little more than a minor lessening in the annual rate of inflation/ appreciation. This is caused by a lower volume of sales resulting mostly from two periods of ultra-high mortgage rates. To date, new commercial construction has continued at a high level because the demand for new office, warehouse and light industrial space has not shown signs of flagging -- regardless of the increases in both costs and leasing prices.

"Investments in real property in the District will continue strong," said James L. Eichberg, president-elect of the Washington Board of Realtors. "Office building projects, with rentals reaching up to $35 a square foot in 1981, should continue to attract investors because vacancy rates are less than one-half percent."

Some development initiative, however, is being dulled by increases in costs of construction financing and the increasing demand for institutional lender participation in ownership -- rather than just financing return -- in major projects. Long-term financing now is often five years at most, with a lender wanting a chance to change the rates on the assumption that market rates will increase.

"We're out of the long-term mortgage market and into an equity position," said Robert Dolan, top real estate investment executive with Prudential Life Insurance Co. here.

Dolan added his conviction that this area's potential for major realty investments is the "best in the country." He also said that 40 percent of Prudential's income is from pension accounts whose managers now are seeking a rate of return "commensurate with the major money markets in order to keep pace with inflation."

Mortgage banker Robert A. Beer has pointed out that high borrowing rates and construction costs mounting at the rate of 1 percent monthly have pushed up projected office leasing rates. He added that the projection made by the firm he represents here (Ivor B. Clark Co.) indicates office building leases could be in the range of $49 a square foot before the end of this century.

Recent construction of new office buildings was described as "little less than phenomenal" by a publication of Real Estate Research Corp., which pointed out that current rates are 100 percent higher than five years ago.

In examining real estate investments generally, there is some agreement that investments in residences and farms are still good, principally if they are to be used by the owner. In Washington, however, recent surges of high borrowing rates have dulled investor interest in new and converted condominium apartments, town houses and some single dwellings.

Residential investors are aware of their inability to get rents that will enable them to meet monthly payments. However, when financing is relatively favorable, some are still willing to feed their initial investment in a condo or co-op town house for a few years until rent increases enable the tenant payment to meet the monthly payments. This investor interest is based on high personal taxable income and the need for depreciation -- plus a likelihood of a considerable capital gain on reselling after five or 10 years.

If the fixed-rate, long-term residential mortgage gives way to the predicted adoption of the renegotiated-rate mortgages, that investor interest in residential properties may be curtailed.

In assessing this investment market, B. Franklin Kahn said the Washington Real Estate Investment Trust's policy of acquiring prime properties is "unaffected by tight money or high rates."

Nonetheless, the currently high rates (in excess of 13 1/2 percent, plus incentive kickers) for available mortgages apparently have prodded WRIT and other dollar-heavy investors to pay cash for acquisitions.

Realtor Justin Hinders, who has observed and participated in areawide realty events for more than 20 years, agreed that depreciation and tax shelters are becoming less desirable because "Congress has taken away so many incentives." Hinders, who foresees increasing realty redevelopment around metro stations in the 1980s, also embraces the conventional realty professional viewpoint that faster write-offs of investments for tax purposes and financing aid are needed to stimulate construction of new rental apartments.

Due to the lack of interest in owning multifamily rental properties in areas with rent controls or the threat thereof, ownerships have become accustomed to accepting high offers from condominium converters who found a strong market among buyers in the 1970s. Local, national and foreign investors show no interest in rent-control properties.

However, the tenant-displacement issue has become emotional in condo conversions, and the cost of converted units has escalated. Thus, there may be belated congressional interest in allowing the current owner of a rental property to claim capital gains tax status -- as opposed to earned income -- if he does his own converting. This procedure is seen as enabling conversion of units to be made on the basis of vacancies and turnover, which often is 30 percent of a big building's units annually in this area.

Meantime, downtown Washington redevelopment is expected to continue strong in the older area east of 15th Street NW.

Even more significantly, it's the area where a recent public auction brought a record $530-square-foot price for a 14th Street corner site that was worth only $67 a square foot to an investor three years ago. Use of the auction process to sell desirable sites with multipurchaser interest may increase as a result of that Oct. 15 event.