We won't know until we see Sony's remote play features fully explained.
So? The Vita exists to let you play your games on the go or in asynchronous fashion with friends and family who are watching/playing something else on the TV.
Sony's bottom line here is to move software because moving software 1. makes them money on royalties and 2. makes their development partners coming back and keeps them involved.
The Vita format is far easier to work on than the PS3, so I'd argue the opposite of your hypothesis will also hold true, why make a PS3 exclusive now when Sony will gladly help you get it on Vita as well? It'll be free sales.
I really like this product for Sony. It's a solid play for the Japanese living room where big expensive consoles are becoming a thing of the past, complete with a nostalgia play on the Playstation brand and strong Japanese PS1 and PSP libraries of software.
It's a legitimate extender/second TV box for the PS4 in any more core gaming oriented household via Remote Play.
It strengthens the Vita's market appeal to developers and app publishers, likely leading to more Vita software and more television viewing apps. It can also serve as a "gateway" to the Vita's library, resulting in people who enjoy portables picking up a Vita to go with it.
It will move more PSV memory cards, allowing Sony to get more aggressive with card pricing thanks to economy of scale profit growth.
Lastly, it establishes their own foothold in the Ouya/Amazon Box/Apple TV/Roku segment, one with a unique set of differentiating features (strongest gaming box in the segment).
All that for a box that likely is at break even pricing or even possibly making a profit. They need to bring the dual shock 3 bundle pricing down aggressively over the next few years, and the same is obviously true for PSV memory card pricing, but if they do both they could have one hell of a Playstation brand Trojan horse on their hands.
Gaikai also becomes a legitimate industry-wide threat with this product as well, stepping up the move into a low cost streaming box future much sooner than many expected.
If this takes off I'd expect the Vita chipset to quickly find a home inside many Sony TVs and Blu-Ray players in the near future as well.