I made a thread predicting something like this a few months back (maybe in November?); it just seems incredibly likely. The figurines would be best used as an optional means of unlocking content within the games, but primarily as collectables. If you don't want to play for the 100 hours necessary to unlock a character, you can purchase the figurine, instead. It has the character's data and automatically unlocks and maybe some small, cosmetic things only attainable with the figurine (maybe stickers, trophies, or character pallet-swaps).
With regards to DLC, the figurines could be released when a batch of DLC characters come out. You can purchase the DLC directly or pay a bit more for the figurine and some added bells and whistles. I think the idea of themed packs could be cool, too. For example, you could purchase a "villain set" with K. Rool, Ridley, and Ghirahim a few months after WiiU comes out. It would cost more than just purchasing the DLC, but might include access to otherwise inaccessible stage music and an Assist Trophy or two.
And Kirks, that's another thing I had guessed! Rather than spend time coding Dr. Mario, they could just plan to release some Dr. Mario figurine after the game is out and devote their development time to something a bit more worthwhile.