Why wouldn't handheld supporters support the Switch? I get that it isn't something they should assume (I suspect we all know that saying about assuming ;-P) but if the system is some sort of blend between console and handheld what would prevent the other developers supporting it? Some sort of major tech difference I'm just not understanding?
The reason not all handheld supporters will necessarily support a home console (even doubling as a portable console) is simply first and foremost, the price. Despite the bigger screen and increased technology, not everyone will want something as expensive as a home console.
Think about it in this way, there's now a "New Nintendo 3ds" which plays certain games you can't play on a regular 3ds, and because it's new it costs slightly more. Take that to the next level hypothetically and say there's a "New 3ds 2" which plays all Wii U console games (hypothetically) but the price point is considerably higher again. Rather than 300 AUD it's going to cost 500 AUD. Understand it plays more games etc.. However, for most of the general public on median wages/ salary, that's a lot more money for something than the average customer may be willing to spend.
The other thing is the DS/ handheld generation who may not be willing to buy a console given that their hand is being forced to buy a hole console and again, pay more money.
With developers I don't know the ramifications exactly. But, for eg if the technology is far more advanced then it may take additional time & resources (= money) to develop something at a lower budget. If the technology is straight forward then it shouldn't be problematic, but I'm simply flagging as a potential issue as we're not sure how handheld developers would fit in. It depends on the complexity of the development kit.
This all comes back to the state of the economy.
People are spending less on luxuries and more on essentials. People are starting to play through backlogs of games rather than "collecting" new ones.
With a squeezed economy also comes squeezed pockets, not only for consumers but for developers, along with squeezed contracts.
In truth Nintendo's idea for the Switch is actually very solid, but may have manifested in a less than ideal global financial context to allow it to flourish.
Of course the wealthy will purchase it, and if it can do what an iPad does for example, the Ninty supporters may also convert just because it's Nintendo.