Also, high school seniors will have a tougher time getting scholarships. There are a limited number of D1 scholarships. With a lot more experienced players around, more of those rides will be taken and there will be fewer available for freshmen.
The 5-star and 4-star recruits will get spots with higher-quality teams, but some guys who would have been taken by P5 schools will find themselves at mid-majors. Some marginal mid-major guys will end up in D2.
When you have more players competing for the same number or roster spots, someone is going to lose out. Some of the losers will be high-school seniors.