The future is now for American corporations, with many of the demographic changes predicted for the work force by the turn of the century already in place, according to a new study released yesterday.

The findings are based on research by the Hudson Institute and update its original Workforce 2000 report, which has become the seminal document on the subject of the rapidly changing workplace.

"What our survey data reveal most clearly is that the workplace of the future is, to a great extent, already here," the institute said. It said the phrase Workforce 2000 might more appropriately be called Workforce 1990.

The original report by the Hudson Institute three years ago has been widely used in the emerging government policy debate over the need for educational and cultural change to help companies develop more competitive work forces. The 1987 study predicted that 85 percent of all new job entrants by the year 2000 would be minorities and women.

The report also warned of skilled labor shortages and the need to come up with ways of managing a diverse work force rather than one made up primarily of white males.

The new study showed that, while 65 percent of the companies surveyed said they have begun to experience shortages of skilled workers, few of them have started developing programs to deal with the problem.

Conducted by the institute in connection with the management consulting firm Towers Perrin, the study was designed to gauge how well American corporations were responding to new work force issues.

The survey involved 645 companies and is claimed by its sponsors to be the biggest of its kind to date.

"The survey companies are literally in the midst of a sea change," the report said.

Women make up one-half of the work force at the companies surveyed. Minorities compose up to 20 percent of the work force for just under 60 percent of the survey companies, and they make up more than 26 percent of employees at almost a quarter of the companies.

But if the new study is any indicator of what companies are doing to cope with the change, the answer appears to be not much. The study shows the majority of the companies have yet to develop new programs to deal with the problems of recruiting, training and managing employee diversity, according to the study.

John Lynch, chairman of Towers Perrin, yesterday told a Senate task force on the subject that "the changes in the work force are part of, and are one of the drivers of, a change in economic organization more profound than any we have experienced since the beginning of this century.

"One of the key changes managers now must deal with is that the labor market is no longer a buyer's market. It is a seller's market."

The biggest concern of most corporations surveyed was the shortage of so-called "gold collar" workers, people with technical skills. These workers are referred to as gold-collar workers because employers believe they soon will be able to name their own salaries.

The study showed that, as employers look out over the next five years, they see shortages in technical skills in almost all employee categories. At the same time, few of the companies surveyed appeared to be willing to spend much on employee training.

Ironically, despite the concern over skills shortages, the majority of the companies surveyed showed little interest in developing new policies to keep their older, skilled employees.