I do not think this game or any first-party title should end up on the PC as long as the maker of the games continues to market their haedware as a necessary purchase to play the first-party software. The reason for this is that it would be a real slap in the face to customers, especially those who purchased the system before hand(imagine buying a Wii U to play Xenoblade Chronicles X or a PS4 to play Uncharted 4 before the games were released because they were announced as first-party exclusives and then later you realize that the company is simultaniously porting the game to other platforms, I think that would somewhat piss people off because they could have used the PC or console they already have or purchased another console hardware they wanted more to play the same game). Furthermore, the game would sell better if it were multiplatform like you stated but it would also take longer to break even and profit due to porting, and again it would anger a lot of people who have purchased systems to play the game.
Also, I do not think you should worry that this will be repeat as the original Xenoblade. I say this because Xenoblade Chronicles 3D for the New 3DS (a system which has a lower installbase than Wii U at the moment) has been available in many retailers at the same price as other 3DS games. Furthermore, the Wii U is not in the same situation as the Wii. With Wii Nintendo could have sold a game, like Xenoblade, in a single region (due to the Wii's decent installbase in nearly all regions) and made a profit without having to worry about potential risks of localizing (I think the risk was the entire reason for the limited localized release of the first game, because like you mentioned before JRPGs tend not to do as well globally and these games require a lot of resources to localize; however, I think after the Wii release of the game they realized there is demand, which is evidenced by the wider availability of the port of the first game on New 3DS). With the Wii U, however, Nintendo needs to localize every game because the small installbase means that most large projects need to be bought by some portion of the entire installbase to be successful, so Nintendo needs to make the games as available as possible (which means no retailer exclusives, no small production run, etc); Nintendo also has to release all of their games worldwide in an accesible manner to satisfy existing Wii U owners.
Lastly, you metnioned that you were worried about the online being discontinued earlier then it would be on PC. You have a point there, but like the PC, many popular games on console have fans who run their own private servers. I know of Wii, PSP, orginal Xbox, and even Dreamcast games that continue to get online support through fan-made custom servers.
