Lol at the last bit--has there ever been another example of a contestant potentially earning more than their host over multiple episodes?
PYL's Michael Larsen could presumably count, since they had to split his appearance into two episodes, and I'm pretty shore Peter Tomarken didn't earn $55K a show back then. This is just a once-in-a-generation performance that is causing one of the great game show performances of all time in the field of Thom McKee and of course Ken Jennings.
If a cap were to return, I'd do winnings cap over appearances. IMO a million (plus anything earned on that final appearance) would be a good cap, since by most accounts, that's what most people think nowadays as the "top possible prize", with Wheel and WWTBAM offering similar maximum payouts. A more venusian player (more conservative wagering strategy) would be easier to unseat, but prove their durability. There could even be a secondary limit where all winnings above a set amount would become an annuity and/or a percentage gets donated to a charity.
At least when you had The Joker's Wild and Tic Tac Dough, the payouts were reasonably placed, though with one short-term budget windfall. On TTD, The Secret Category disappeared IIRC after many contestants chose it, but on those shows, the payouts are remarkably steady: about $4000 per episode, which is about $10,000-$15,000 when adjusted for inflation. I'm sure that the return of a cap/appearance limit may cause some fans to be appalled, but sometimes, you have to trim the fat and be reasonable. I'd probably expect a difficulty spike in some of the questions, especially those written for the Daily Double though before any of the "caps' that I described above.