YGO? Yu-Gi-Oh! is still alive and well, and Digimon is having yet another game released this Spring in Japan, and all of the DS games before it were translated. It's not like ZOMG SUPER POPULAR, but it's still alive, while YGO is doing nice. At least it's not in season limbo. But, Bandai is still releasing Digimon products (mostly CDs and the occasional game), so that's good. Neither are dead.
Pokemon and YGO both overwhelm Digimon, though (YGO is the best selling card game, Pokemon is best selling RPG series). I will point out something that backs up your main point (aside from YGO and Pokemon keeping the core game the same while innovating a lot).
The next Digimon game that's coming out is Digimon Story... 3, as in, it has the same core gameplay as two earlier titles. Why? Because it's what works and actually got new fans. They were actually somewhat good; they tried changing it up to a V-pet thing after DS2, but that didn't go well at all. So, they are back to what people liked and what is widely considered the best Digimon games ever made (which isn't saying much, but Digimon games that are actually enjoyable are win by default).
Doesn't mean it will sell better than YGO and Pokemon, considering the other two are STILL somewhat popular while Digimon is, uh... Not very popular. Anyways, back on topic.
I hope they do add some more Dragon Pokemon, I like Dragons. I wonder what innovations they'll bring this time? We'll see.
