That's what you hope yes, but you dont know how much it could sell with a decent marketing. even Ninokuni sold very well in the west.

They already have been "stupid enough " to make DQ Heroes on PS4 and not on 3DS, because they know the fanbase move quickly, they'll buy the platform with the next Dragon Quest so at the end, it's better for them, allowing them to use that opportunity to expand the fanbase to the west

Because, since the next one will be on big screen, PS4(/PS3) is the best choice for SE

Wii U is best option right now in Japan. 

A difference of only 1M is not enough to make a real difference in sales, especially when the PS4 is supported by third party in Japan, they consider the futur of Dragon Quest, they know it's a more popular console, even in Japan, surveys put PS4 as the most wanted home console to make a DQ, and like i said, fans will go where is the game anyway, and since they want to expand DQ name, PS4 is the best choice

All I'm seeing here is you "hoping" that what Horii said is fact. And also hoping that what the guy quoted in the OP says is just throw-away blabber. (By the way, DQX got good marketing. It did okay in the West, but it still didn't reach anywhere near a million.)

But it's true, I'm incapable of predicting SE's next stupid decision. Right now we'll just have to keep following their crumbs until they actually decide to give us useful information.

Wait for TGS then, maybe this is the good one.

Just some speculation on my part.

Yuji Horii says the game is in development for the big screen not mobile/handheld.

SE releases DQ Heroes on PS3/PS4, thus at least to a degree signaling to DQ fans "this is where DQ is going", remember the Wii got some spin off DQ games as well before eventually getting DQ X.

I recently read that SE thinks that FFXV is crucial to the success of home consoles in Japan and that if it fails there might not be much of a home console future over there. Read here. This sounds like a certain disregard of the Wii U already.

I cannot think of a single SE game in development right now that is coming to Wii U. Now granted the Wii didn't get a ton of SE games either, but it got a couple at least. The Wii U only has the DQ X port for now, if I'm not mistaken.

So while non of this is proof of course, I still think that we can book DQ XI on PS4, possibly even exclusively, as a very real possibility for now.

Development cost differences are largely unimportant for a game of this scale. It's going to cost millions and millions regardless because it'll have a huge team and a huge marketing campaign behind it.

For the people who think Wii U is a better choice because of a 1 million difference in user base are not looking long term. SE have already commited FFXV and KH3 to PS4 to increase install base. They will likely captilize on this and extend it further with DQXI. DQ Heroes can't hurt either. What you're seeing is a long term plan here. It really just feels like some people here just want to shut their eyes, shake their head and say no it won't happen because they don't want it to happen..

 I believe people are taking the big screen comment to be final, but there is a lot more to it. Yes, it may come to PS4, PS3, wiiu, Xboxone, PC and others... But is SE really going to pass on releasing DQXI on the 3DS? 

 If Yokai watch can sell more than 3 million copies in a year, should DQXI not sell the same or better? DQIX is the best selling DQ ever, skipping 3 millions in Japan only is crazy business.

 Even if they were to release DQXI on all major consoles available, I do not believe it may even match the 3DS sells. I mean, DQXI could even sell 3 millions at full price on two or three weeks in Japan alone. That number is simply impossible to reach if they release it on big screen consoles only.

DQIX sold well in the west only because Nintendo heavy advertisement.

 A late port is possible, but business talking, skiping the 3DS is just crazy and money wasted.