Of course it will have an effect - you get four years of eligibility and the NCAA is telling UConn's roster that they will only have three opportunities to play for a post-season.
Next year's UConn team will play until about the first of March and then stop - no Big East, no NCAA, nada.
I'd certainly consider my options.
I get you have four years of eligibility. I'm only talking about transfers. I get why this could push Lamb/Drummond to leave for the NBA.
Let's use Player X as an example. Player X is going to be a non-senior. He wants to go pro after next year. He isn't ready for this year, but feels he will be by next year. Why would he transfer? He would have to sit a year at the new school. His goal is to go to the NBA after next season. Why not stay at UConn, play in the regular season and be evaluated on the regular season? It's that or be evaluated based on not playing a game next year.
Now let's look at Player Y who might be a 4 year player. What is his best option? If he transfers he has to sit a year, but he gets four years of eligibility looking for a championship. However, prior to this news he didn't want to leave UConn. Now wouldn't it be better to stay at UConn and redshirt next year?
If the player was already considering transferring, this might push them to transfer, but what do they gain? They still have to sit a year, if they really wanted the 4 years of eligibility they could just redshirt a year.
I am fully aware you were joking with redshirting everyone and playing scrubs/walkons, but if Drummond, Lamb go pro, why not redshirt any player who wants to redshirt. It's the equivalent of them transferring in terms of eligibility (Bradley aside), at least as far as I understand the transfer rules for this situation.
I am under the impression Oriakhi is the only player that could play immediately next year.