That depends on what bugs get fixed. It wouldn't be so hard to fix popular levels that run into problems anyway.

Or... I suppose after new versions of JJ2 are created with the source, it could be made so that JJ2 could run older levels as if it was still 1.23/TSF and whatnot. But that's just a thought.

Nevertheless, I agree it's somewhat pointless to want the source at this point, especially since there are other more realistic projects around like a scripting language.