From looking at the Euro Festool sites, it appears that there are separate table saw and router table setups. What I think would make far too much sense would be to have an add-on table that would connect to an existing MFT. You could have a substantially smaller table (more narrow, barely large enough for the saw or router to fit into - maybe 12 - 18 inches wide) that would not necessarily be ideal on their own, but when coupled to an existing MFT would offer plenty of options.
For example, you could offer a table saw "MFT extension" that would allow you to change the orientation of the table saw. This would allow you to rip very long pieces, and then turn it 90 degrees, and cut very wide pieces. Of course you can do this with one of the existing saws, but for those that really want or need a table saw, this might do wonders. Additionally, you could create all sorts of fence accessories that would leverage the existing table rails / hardware.
Same idea for the router table - just connect it to an existing table, and then you've got access to all of the toys on your MFT to use in conjunction with it.
You could also make a planer extension. Imagine being able to leverage your MFTs this way. Mill your lumber on your two MFT setup (with the planer connected in between the two). Of the three "extensions", this is the one that you couldn't easily convert back to general purpose usage immediately after. Maybe there would be some way to lower that portion, and put a MFT filler plate in over it.
When the saw or router weren't in use, they could be lowered, allowing for larger table work space afterward.
Here's a (very) simplistic overhead view of what it would conceptually look like:
I'm sure someone else has thought of this, but I figured I'd dogpile on.
(sorry for the big image, dunno how to scale it down... running at 1920 x 1200 here)