Could an IJ5 and IJ6 be better? Sure. Indy needs to stop being an Action Hero in quite the same way, and the plot needs to be a lot stronger, but there's no reason why it couldn't work.
Of course there are also lot of ways it could go horribly, horribly wrong …
Reshared post from +GeekTyrant
Harrison Ford in Negotiations for 2 More INDIANA JONES Films
http://geektyrant.com/news/harrison-ford-in-negotiations-for-2-more-indiana-jones-films

Recast… go back to the 30s. … where Indy belongs
I agree. I think a reboot of sorts would be a better way to go.
I think a big chunk of where IJ4 failed, at least for me, was the supposed "passing of the torch" to Shia LeBouf's character. It didn't really flow for me and I thought they put too much focus on Mutt and not enough on Indy.
I agree that he should step back from "action heroics"….that's a younger man's game. Maybe Indy went on to become a government agent, of sorts, or an advisor on occult artifacts?
Harrison Ford hasn't turned in a decent acting job since….. ummmm. … Regarding Henry.
Also, part of the problem is that Crystal Skull was emulating a cold-war genre store, and that made folks upset who wanted more Pulp stories like the original trilogy.
+Mark Means I didn't mind Shia LeBouf as much as others — but since he has "quit" acting we won't be seeing him again, I guess.
+Nick McIntosh A reboot might make sense — but since the context here is Ford pushing to play the character again I don't think that's on the table.
+Isaac Sher I have to admit, though they behaved exactly alike, there's something viscerally different between Nazis and Commies.
Yeah, I can do without Mutt. The idea was alright, but the execution was weak on that character. Shia wasn't the worst person they could've cast for that, but he certainly wasn't the best either, especially now.
Personally, I think a serious Indiana Jones cartoon series would be a great choice.
Considering that Disney and not Lucas is in charge now I think there's a decent chance they could be good movies. Lucas lost his mind a bit somewhere along the way. Hire Roberto Orci and Alex Kurtzman to write it and it could be pretty good.