I think in the past 12 years, TPIR has covered just about everything I would've love to see as it relates to a themed show. Going forward, I wouldn't mind seeing...
A show or a week of shows where the theme is shows featuring line-ups from a past show where something of significance occurred. For example, the show where a women (that day's eventual winner) won 3 Strikes + for over $40,000 within her prize and then $11,000 in the showcase showdown. That line-up included Clock Game, Grand Game, 3 Strikes +, Danger Prize, Check Game, and Five Prize Tags.
Maybe not the best example, but two other examples from that season and many others include Credit Card and other games that have been retired.
Speaking of which, a show that exclusively has every pricing game that has been retired. Or a week of shows that feature a game or two that has been retired. That may not ever happen; there are some games that don't need to return at all, but some that could surface one time only
Like the April Fools idea, JayC, and obviously the essential workers/first responders show/week of shows. With the older sets for games, I'd love to see someone recreate the original set of certain pricing games for some of the pricing games for an April Fools episode. At least most people in the studio audience won't get it, but some of the LFIT and I would!