You mentioned "Wii": does that mean you intend to add support to "tpl" graphics and other GC/Wii-specific formats (like you intend to for PSP with GIM support)?
Yes, the roadmap for future versions of the tool would be to add support for mipmap TIM2 images and GIM files. Then, adding support to tpl images found in GC/Wii games.
Any way to include tree support and TOS rebuilding support for PS2 (maybe PS1 and PSP if possible) to the limited extent possible, even just as a GUI for other existing tools for practical reasons?
I am not sure I got what you mean. You mean ISO rebuilding?
Also, is there any possibility to include (already-made) TIM support within this tool for completeness sake?
This is not considered a main feature right now, but it is not excluded. As for now, there are many good tools that can deal with TIM images.
Any chance -and that's a *big* stretch- to make the tool as comprehensive as Tinke or CT2 by including compression/decompression support for known formats like slz (tri-ace stuff), cpk, pkg (whatever Square Enix is using for PSP releases) and the like, instead of resorting to command line? A GUI would be really nice.
It is very unlikely. The main goal of Rainbow is to manage specific graphics formats. Compression and archive formats go out of this scope.
Even if a GUI would be nicer for many people, I still think that for such kind of files, a command line tool would be more suitable (since they can be used inside scripts to rebuild the whole structure of the game disc).
What do you think about the feasibility of including Saturn graphics support (attempts were going underways back in the late nineties for a graphical editor but fizzled out due to a complete lack of interest)?
I did not dig too much into such formats. But if I manage to find enough documentation and good debuggers for such a platform, then yes, it is definitely possible that Saturn graphics support wiil be added.
Or making something like Tilemolester but with more options, better coding, and much more flexible clipboard handling (like with CT2), included within the tool? (one of the aspects I wish Tinke included. It does have a hex editor that's awesome to use on the fly for any file under the arborescence)
As I said for the previous quotes, this would go out of the main goal of this tool. So, no there is no plan, right now, to extend the program with such features.
P.S. It seems to be something wrong with the image link on this news. May some staff member fix it?