We also had polls before the lauch of Ps4 with results where the Wii U obliterated Ps4.
Switch is a niche product that targets niche market. It's trying to replace smartphones & tables in mobile gaming market, and consoles in households & living rooms.
If it doesn't come out with many great exclusive games (that will WOWWww gamers) in 1 year after its release date, then it's DOA. They did an awesome thing with Gamecube, and that is bringing RE:Remake & RE:0 which i love to death. But did it work? No, it didn't. And now they only bring a remastered downgraded Skyrim. What a joke. Gamecube was DOA because Gamecube had nothing in its weaponry. Switch on the other hand only has joycons to overcome all its weaknesses (weak cpu & gpu).
I say that the Switch is DOA, but we can only know for sure after 6 months after release(1 year at most). The Ps4 & X1 killed Wii U 1 year after release, Wii U could still breath fresh air for 1 year without competition. Switch will fight Ps4, X1, smartphones, & tablets in the market. Logically, Switch is DOA.
Also let's not forget that PS4 and X1 can also produce hardwares similar to joycons if it's a good gaming controller. Remember that Xbox had Kinect and Ps3 had Playstation Move, they produced those hardwares to compete with Wii mote. And what was the result? The death of Wii.
Let's face it guys... Switch will die and is a DOA product.
I've got a Pro, but now I feel like i want to replace the PS4 in my living room. So personally I will go Pro (again :).... I think the Switch is a very interesting concept and especially for me as I travel a lot but I am not a fan of nintendo games.
So though I am Pro, I think my son is wanting a switch, so ultimately Nintendo will get a sale from me anyway... doh.
On the grounds of launch titles, current library, price-to-value ratio, etc. it has to be PS4 Pro at the moment. A wonderful choice for your only console. Switch is a fantastic complementary device however -- a much better proposition that XBOX One or Scorpio (unless if MS backtracks and allows exclusives on Scorpio). For now, PS4 Pro it is. Switch simply doesn't have the library to compete yet.
I bought a PSVR which made me buy a PS4 Pro which made me buy a 4K TV. The pro is a much better console on paper but, at the end of the day, the improvement is disappointing or negligible (IMO). I jump between the Pro on my 4K Bravia and the vanilla on my 1080p Vizio all the time.
The PS4 itself is still a better purchase than a Switch but you're going to be let down if you're expecting a big difference. Think DS Lite vs DSi (only less noticeable).
Sell your old PS4 get a pro and also get a s/hand Vita for remote play. Then you can play all your ps4 games around the home and garden with Switch beating graphics using the Vita for free and no need to pay out for expensive Switch cartridge games, effectively a 4 terraflop portable. Also get yourself some igrado's or other Grado headphones for when playing on the Vita for incredible sound quality. The Vita also doubles as an extra ps4 controller for additional players.
Keep your wii u for Zelda of course.
As a Vita owner who uses Remote play and still buys Vita games, do not consider this option. The Vita lacks too many buttons and using the touch screen as buttons is a horrible compromise. Some games are unplayable. Games look INCREDIBLE on the small screen but the cons are too much (lag, worse analog sticks, running two consoles just to play one game, etc.)
With that said, unless you're a hardcore Nintendo fan (like me) wait on buying that Switch. Not enough content at launch.