Nintendo has always been open to the genre regardless thier rhetoric in the previous generations.
Maybe you're too young to remember, but former Nintendo president Yamauchi was
quoted in the N64 years as saying that "RPGs are for depressed gamers who like to sit in their dark rooms playing slow games" and RPGs were (to him) "silly and boring". There were a lot of sour grapes between Nintendo and Squaresoft back in the day. And I'm curious how you can say the company as a whole is open to the genre when we have NoA refusing to publish the Operation Rainfall games when they have
nothing else releasing on their console before or after Zelda.
Also, no system has ever launched with an rpg of this caliber at or near launch. Sony became the home for console rpgs becuase Sqauresoft built the audience with FF7. The same could happen now with the WiiU and DQX.
DQ X will never be what Final Fantasy was at its most popular. I don't think any JRPG could be, honestly. The genre's nowhere near as popular as it once was outside Japan, and FF7 was the perfect storm of new technologies that people had never before seen to that degree. That will not be the case with DQ X.