Yes and no. There is absolutely still tons of opportunity to build a team of veterans who have been with your program. In fact, most of the most successful programs recently have built that way - Gonzaga, Villanova, Baylor, Michigan. Now, these teams are also certainly getting impact freshmen and grabbing transfers, but a lot of their transfers come earlier, not as one-year 'make a run' type guy.
Programs like Duke, Kentucky, UNC, etc. are finding it tougher than ever to achieve consistency because they're trying to play that 'get a bunch of one-year guys and make a run' game all the time.