That's a very harsh statement. Complicated design did not stop the PS3 from doing well with third party support. I think if the system sells well enough, it will garner the developer support.
1) The Nintendo 3DS hasn't got "underwhelming sales". The Nintendo 3DS broke the Japanese record for most hardware sold in a month during December.
2) He claims that the WiiU is too complicated and that "they should stop relying upon the strategy that got them here, as it appears to no longer be working". What rubbish. The jump from Gamecube to Wii was an incredible jump. Going from a traditional controller to a motion controlled remote was a very complicated change (at the time) and it proved to be an amazing success! The same with the DS; they went from a single screen to a dual-screen setup with a touchscreen. That's much more 'complicated' than the GBA.
Adding a tablet to a controller isn't such a complication for developers - well not in my opinion. If you utilize it as a DS (with two seperate screens) you're halfway there and third party developers have proven quite capable of handling two screens.
Besides - tablets is currently a very desirable gadget. Look at the iPad. Adding such an element to a console can be nothing but good news.
It's Sony and Microsoft that needs to up their game. Besides adding Kinect and Move their consoles have always been very "traditional" and the Wii outsold by millions.
Also - if you "build it" and manage to sell millions (like the Wii, DS and soon the 3DS) developers are stupid to not to support it.
Meh this is just my opinion. I think these "analysts" are always biased in some way. Everyone is always sceptical and negative about Nintendo and their products but so far Nintendo has been smiling all the way.
The Wii was underpowered but it was cheap, the Wii U is going to have the same power as 7yr old current gen consoles but be more expensive and have none of the games. It's going to be a hard sell to both customers and third party publishers which when you look at it had very limited success on the Wii.