This one may actually be the most likely of the crazy ideas here because of Snell's contract status. The Astros very clearly want to add a starting pitcher at the trade deadline and if the Cease rumors are any indication, they are not looking for your standard back end of the rotation types. This is a front office that is looking for an impact arm for 2023.
Lost in the shuffle of all of the usual names that have been bantered about on the starting pitching market is Blake Snell. Snell has been pitching his brains out this year to the tune of a 2.71 ERA for San Diego this season. He has walked too many guys to be sure, but he is also only giving up 6.5 hits per nine innings pitched which has taken some of the sting out of that problem.
However, Snell's biggest selling point is that he is a pending free agent which dramatically decreases the price he could command on the trade market. He is making $16 million this year, but he is set to hit the open market after the 2023 season. The only reason that he hasn't been discussed as a trade target more this season is because everyone assumed that the Padres were going for it. As discussed above, that is far from a sure thing anymore.
Even the Padres decide not move guys that are under control for longer than this season, there is a case to be made that they should still trade Snell away given that he could just walk after this season. If that happens, the Astros need to be involved. Snell is too good to just give away, but he shouldn't cost an arm and a leg to trade for if/when he becomes available. If Houston could pull that off, it would fill a huge need with arguably the best arm on the market.