Is portable gaming dying?

Portable Gaming was a part of my life. I both owned a DS Lite as well as an original PSP. Now we have the 3DS XL (or the 2DS, if you prefer that type of design), the new PlayStation Vita, and the Nvidia Shield ("What about the Razer Switchblade?"). What happened to traditional handhelds, now with iOS and Android flooding the gaming market with very few hardcore games like ShadowGun, the fun but repetitive Dead Trigger 2, and Limbo? What happened to the handheld market, that had lots of products like the GameBoy, TurboExpress, Gizmondo, Neo Geo Pocket Color (but GameBoy being the clear winner)? What is the future?