Just chipping in a sec.
I think we have great tools and a great modeller in Blender. Cyan knows damn well what we are using and I think it'd be foolish of them to start building something that already exists and already has an enthousiastic userbase.
So I don't consider 'other tools' an issue. If they do surface however... like Hoikas said about PRPExplorer... some interesting competition might bring us the best.
Most important for us (read the devs, but with our feedback) is to make sure the tools are usable for as many people as possible. There will be some tough limitations, but steps can be taken to enhance things. Custom UrU GUI in Blender, sample scripts, base scripts,etc. Refering to an example posted a few pages back: the opening of a door could be preprogrammed with a reference to the animation of the door. All other stuff (clinking the door, disabling of avatar(s) during animation, etc.) could IMHO be standardised. Wouldn't drag and drop of base funcionality like that be awesome. Game logic like puzzles is a whole other ballgame off course, but doors, journals, etc.... could probably be GUI driven in Blender.
My biggest fear is that the base of writers won't grow enough because of the learning curve.