I will take a wait and see approach. We will know how things look after a few months of the next-gen consoles being on the market.
But considering that pricing hasn't been revealed... And Sony hasn't showcased it's new console, policies and so forth, they could make a big blunder. Or they could do the complete opposite.
Can go either way until we know all the details... Until then it's all just speculation.
I very much so am a 'wait and see' kinda gal, but I think History has proven that Sony is going to knock it outta the park. They are responsible for the 1st, 2nd, 3rd, and 5th best selling home consoles of all time (With only the Wii in there at #4), and even at their worst they outsell Microsoft at their best. Long term, sony almost certainly has it...but the last 7 years Sony has been knocking it out of the park while Microsoft has been failing, flailing, floundering, and falling flat on their face since day zero.
Right now, the Playstation Brand is remarkably strong, while the Xbox is potentially at its lowest point. While Microsoft has done well convincing people to buy their consoles with flashy promises of exclusives and features, I think after 3 generations (2 and a half of them being flops or massive disappointments, with only the first half of the Xbox 360's generation proving successful), people might very well have moved on and learned their lesson.
I think first month sales will be pretty similar for both consoles, but after the initial rush of folks, I'm confident Sony will end up beating Microsoft at least 2:1 again. Maybe even 3:1 long term. Nothing about Microsoft's output in the last 10+ years makes me think they have what it takes to even be in the same market as Sony.
My Console Library:
PS4, PS3, PS2, PS1, WiiU, Wii, GCN, N64 SNES, XBO, 360
3DS, DS, GBA, Vita, PSP, Android
Top 6 this generation:
Bloodborne, Sekiro: Shadows Die Twice, God of War, The Legend of Zelda: Breath of the Wild, Dark Souls III, Red Dead Redemption II, Rock Band 4