In order for the Wii U to reach Dreamcast or Gamecube status, it's going to have to get a good list of 3rd party exclusives. Those quircky games that can only be found on those systems - things like Cubivore, Baten Kaitos or Billy Hatcher on the 'cube or Power Stone (I don't count the PSP mash-up), Maken X or Sword of the Berserk on the DC. The only non-shovelware 3rd party exclusives I know of on the Wii U right now are Lego City Undercover, Zombie U and The Wonderful 101 - and 2 of those were published by Nintendo.
Don't get me wrong, I *want* this to happen. Those quircky exclusives that a first-party platform creator just wouldn't put out are what give a console its personality IMO. There are tons of great 1st party games on the GC, but when I think about that platform those aren't the first games that come to mind. Heck, those quircky exclusives are why I feel the PS3 has so much more personality than the 360 ever could.
But time is running out. If there isn't a turn-around for the system - and fast - then its not going to happen. I'd go so far as to say that if sales don't greatly improve this year, then next year may be the last year even Nintendo supports it. Not only are the big third parties not making exclusives for it, but many are pulling support for it altogether. I'd still say it's a toss-up whether the reported Watch Dogs port ever releases or not, and if it does that may very well be the last big multi-plat game it sees - again, unless sales turn around in a big way.
For this to happen, I think a price drop to $200 is going to have to occur. $300 just puts it too close in price to the PS4 & soon-to-be-Kinect-less Xbone, and with the massive upcoming lineup those systems are touting it's too easy to justify spending an extra $100 to get a more "future proof" system. $200 would put it far enough away from them to stop it from being directly compared to them as well as make it a very attractive option for parents who don't want to spend that kind of cash on a game system. It would also make it far more attractive to PS4/Xbone owners who want to pick it up as a secondary system.
Don't take anything I'm saying as a slam on the Wii U. I recently picked one back up, and I'm glad I did. The system is absolutely worth owning just based on the first-party software that's out now & will be releasing soon, no doubt. It's a great system hardware-wise. Very underrated. It may not have the horsepower of the other 2 but it has all it needs - it is not as handicapped in that area as the Wii was. I want to be proven wrong - I WANT the system to be a success. Maybe tomorrow's launch of Mario Kart 8 & the game/system bundle will move units. Maybe upcoming games like Smash Bros & Zelda will get people excited enough to buy one. Heck, hopefully we'll get some awesome E3 game announcements that will push sales & get everyone behind the big N again. But whatever is going to happen, it needs to happen quickly.
EDIT: I forgot about Monster Hunter as another big 3rd-party exclusive.