After further thought, I think the failure of Kenner's Indy line was probably due to Kenner's own success with Star Wars than anything else. The Indy stuff was good, but I think it was out around '82 and '83, which was right when the Jedi stuff was coming out. Plus, their 3 3/4" G.I. Joe line started up in '82, as well. Competing for shelf space (and consumers' disposable income) with those two lines had to have been a tall order back then. I think that's it--it was just a victim of bad timing, probably.
(And would it be possible for a mod to change the title of the thread, just to "Indiana Jones 4" or something? If and when it gets made, Lucas won't be directing. . .)