I've heard that there will be a DQ mmo, however, I haven't heard whether it'll be numbered. I wouldn't bet on it, but how many people would have said the same thing about DQ9 being on DS? Anyway, I thought that this would be a DS mmo sort of thing at first, but I guess that ain't true.
If they do make a DQ mmo they might not make it part of the main series. They might call it "Dragon Quest Online" or some such. If I were a betting man I'd take you up on that bet, except for the fact that I may have to wait 20 years to collect my money when DQ16 comes out. I mean, I may as well say that DQ will eventually be a fighting game, and it will happen between DQ11 and DQ48