An Idea
While I have a major issue with a reboot of Indy, especially while Harrison is alive , I do think that either one of these could be a good idea:
1) A series of big screen movies with a young actor, set from 1920-1933 or so. The series wouldn't conflict with the YIJC or override them, and might reference the events from them once in a while. However, they would basically be like the Harrison films albeit with a younger Indy. Essentially what the YIJC would've been if the series hadn't been cancelled (The meetings with Belloq and their brief friendship, etc)
2) A series based on the Bantham series of books, or the comics. Movies are adapted from novels all the time and the stories of the books could be tweaked to fit in timeline wise with the YIJC.
Neither of these would truly touch into the era of Harrison's Indy and would exist in the same continuity as both the Films and the YIJC; Not a reboot. The 15 year gap from Hollywood Follies to ToD offers a long time range for a lot of great stories. Some of them could be adapted from the Bantam series--you have a lot of great, classic Indy material right there, plenty of artifacts.
Basically, not a reboot but a film prequel series. It'd be perfect, really--If an Indy V with Harrison is truly an impossibility.
I think a lot of people have wanted to see Indy in the 1920s--When he romanced Marion, had the fall out with Abner, etc. Quite a few of the Bantam books would make for great movies. We could finally see why the Sultan of Madagascar would cut Indy's "misunderstanding" off if he ever returned; When Indy was called a grave robber in Honduras, etc.
A lot of great moments, and a great way to revive the series and take it back to Indy's more rogue-ish years, with an actor capable of being engaged in Raiders or TOD level action scenes.
If none of this comes to pass, we still have the YIJC, the dozens of comics, the video games and the Bantam books to fall back on if we have Indy cravings.