I'd say that there already is a semi-sequel to SMB 3: the eReader levels for Super Mario Advance 4. If you are a Mario 3 fan and have not yet played through all 32 of those levels (both the US and Japanese cards), you are truly missing out. They are all Mario 3 - like levels in their charm and creativity, yet also combine items and enemies from Mario 2 USA and SMW. I enjoyed these levels far more than the entire NSMB.
Below is a video of one of the Japanese levels, which were once very hard to acquire in any format, but I put together a .SAV file with all 32 levels opened a while back which can be used on either an emulator or a flash cart for the full experience; let me know if anyone wants it (moderators: it is not a ROM but a save file, so offering it here should be fine, yes?).
Here's what Nintendo should do: put all these levels together as a package on WiiWare, then also create a simple-to-use, visual level editor with an online feature so that anyone can create a Mario level using combined elements from all the old games and post it online for others to enjoy. Feature an exceptional level every week, etc, and make it a great community. Fantastic work has been done in the world of SMW Rom-hacking for ages, but downloading IPS patches and all that is too much of a barrier for everyone to participate.
