Absolutely nothing will change if one and done changes. The elite schools will still be elite and schools like UK and Duke will still get the elite of the elite that comes to school. UK will replace the kids that go pro out of high school with other elite kids that might not be as good but will form the foundation of more solid, cohesive team due to smaller roster turnover. Also the kids that weren't projected as first round picks will now be forced to stay in school and will allow UK to field much more experienced, talented teams.
If the 2 and through or 3 and through rule had been in place UK likely wouldn't have gotten Cousins, Wall, Davis, Gilchrist, Knight, Skal, Townes, Nerlens, Randle, Fox, Monk....but...kids like Booker, Bledsoe, Ullis, Teague, Briscoe, Orton, Young, Murray, Lyles, Lamb, etc...all would have been at UK for multiple years and formed teams that would have likely been much better than the teams UK ended up with.
Bottom line....I would say the only outcome for college basketball fans that weakens UK at all is if the NBA goes back to the old rule and places no restrictions on when they can go. If you're looking for the best way to take power away from Cal...the current system is the best option as I don't see them ever going back to the old way. Cal has shown that even with an absolutely insane abundance of talent that its difficult to win a title with inexperience in March.