For what it's worth, this seems like an internet rumor that is likely not true.
1) It's easy to blame "a source I cannot reveal" if it turns out not to be true.
2) Half the message talks about the Champions Classic as if it's indication of something. I don't see how it is. Tennessee and Louisville are recognizable brands in WBB, but don't have any real box office players for next year. That will be true of Iowa next year if Clark doesn't return. Booking Iowa on the mere possibility she does is a solid investment.
3) It's not obvious why Bueckers and Clark would get the same offer. Clark clearly moves the needle substantially on viewership. Iowa without Clark will get a fraction of the views. I'm not sure that's true of Bueckers. UConn itself is a huge brand. So long as UConn is good, my guess is it would get fairly similar views with or without Bueckers. If Clark's team knew Bueckers was offered $2 million, my guess is they'd ask for quite a bit more.
4) The general consensus the last couple weeks (at least) has been that Bueckers would likely return to UConn. I don't think her announcing that at senior night is a confirmation of anything either.