Cities of the 1970s, fighting problems of financing and deterioration, will become new battlegrounds in the 1980s as energy-conscious suburbanites return to them and struggle with the poor over who should live there, several urban specialists said this week.

To survive, the cities and their ofter-neglected central business districts must cater more toward energy conservation through more efficient mass transit systems and center city outdoor malls, escalators and non-automobile people movers, some of the specialists said.

On the other hand, the cities' poor will be fighting to stave off encroachment by the more-well-to-do seeking entree back into the cities and subsequently displacing them, other specialits said.

In the City of Brotherly Love, for example, there already is little love left between poor minorities and their sub-urban brothers who are coming back to the cities, one panelist warned.

"the struggle in Philadelphia in the 1970s is who in the 1980s will occupy the geography of Philadephia," said Shirley Dennis, director of Delaware Valley Regional Housing Services. "minorities will become the majority in the cities."

Dennis was one of 17 panelists in special workshops on the problems of old eastern cities as part of the 75th anniversary meeting of the Association of American Geographers. Three panels of urban parctitioners and academics discussed revitalizing the cities' central business districts, housing concerns and mass transportation.

The panelists reached few conclusions except that the city will be the popular place to be in the next decade.

During the "return to the cities in the next 10 years . . . the economically strong will push out and walk over those wo are economically weak," said Leon N. Weiner, president of a Wilmington, Del., building and development firm. "in-city locations are highly desirable."

"many of my colleagues are afraid to say downtown is back," said Leo Molinaro of the Rouse Co. of Columbia, Md. "but it is coming back. We're now beginning to get rid of the prejudice toward 'urbanism.'"

One aspect that is helping downtown areas is the increasing number of people willing to live there, Molinaro said.

"new residential development in downtown is making the difference," he added.

What is also critical to the survival of the cities is energy conservation, one panelist said.

"public transit is the key to development in urban areas," said John Jameson, deputy commissioner for transportation in New Jersey. "we must give immediate attention to the needs of the pedestrian."

Scarcity and high cost of gasoline will force shops and offices closer together, Jameson said. "i envision shopping center parking lots turned into buildings connected by people movers."

But Patricia Burnett, a professor at Northwestern University, said that half the people in metropolitan areas don't use mass transit because "they are so far away from it. It's not accessible."

John Bailey, a partner in a Philadelphia-based mass transit consulting firm said that, in addition to the deterioration of buses and subway cars the bus-manufacturing and mass-transit industries have faced and will face severe fiscal problems if proposed U.S. Department of Transportation regulations are implemented requiring special provisions for the elderly and handicapped in mass transportation systems.

News of the proposals "completely disrupted the bus manufacturing market," Bailey said. "the market for buses dried up for a couple months, one company went out of business and one sold out to an aerospace company. Many engineers agree that it's impossible to build buses today to conform to the regulations. Chances of mechanical failure of the buses-like throwing a man or a woman in a wheelchair off the bus-are extremely high."

The regulations would make mass transit service more expensive than an average taxi ride, Bailey said. CAPTION: Picture, Typical of urban revitalization in the D.C. area is the clean-up job on these town houses in the 1300 block of Vermont Avenue NW, just off Logan Circle. Sermac Systems, which is doing the work, uses chemicals and medium pressure water sprays to remove grime from the brick and metal facades. By Jack Hayes for The Washington Post