Here's a bit of an article from the IJ Ofiicial Site. It's from February 2006...
"When Indiana Jones and the Last Crusade was released in 1989, it came as no surprise that toys were not produced. "I think we learned our lesson at that point," confesses Roffman. "Number one, we didn't think we could really get a toy company interested, and two, it didn't make any sense for toys. It was a different time period than today. I think you could do toys today based on Indiana Jones, not so much because it appeals to classic boys' play patterns, but because there's such a collector market. If you did really nice figures, and vehicles too, I think there's a market that would buy them."
Roffman suggests that should another Indy film be released, a new toy line would definitely be considered. "I'm not sure it would necessarily be 3.75" action figures, but something that's more in line with what we've done with [Star Wars] Unleashed -- a larger scale, more detailed action figure."
I'm betting we get the 3.75 ine with a vehicle or two, and some unleashed size pieces.