Old third party titles will be sold on the Wii U eShop to help the Nintendo fans play catchup with eveyone else.
No they won't. That would be a waste of resources. If you want those games, buy a PS3 or 360; they are definitely worth it in terms of exclusives.
I think you are both half right. I don't think every third party game will show up on the eShop, but at the same time there's not going to be none at all either. The answer is somewhere in the middle: there will be
some. Exactly how many that will be is impossible to predict.
And as far as it being a "waste of resources", its not... companies like EA are notorious for milking their games to death over as many platforms as possible. I think the fact they are bringing ME3 to the Wii U is solid evidence the same is going to happen with other games over the eShop.
It also helps that the WiiU architecture is so similar to that of the 360. This will making porting the old games over easy and inexpensive. I don't know what it costs, but if there is a profit to be made it will be done.
Why buy a $249.99 PS3 or $149.99 360 (plus a hard drive) to play these exclusives if they are coming to the WiiU anyway? Many people only own one console, so having these games come to the Wii U would be a great opportunity for them to catch up on these that they missed by only owning a Wii these last 6 years.
Since this is a Nintendo fan site I don't think anyone (that should go double for the Staff, btw) should be telling people "the Wii U is not for you", or "buy a PS360 instead". If you can get all your gaming needs done on one system then its better that it be a Nintendo system.