I mean, will the market let them?

PS4 currently has 63,87 % market share between the two, and personally, I believe that percentage will grow larger in the coming months.

Why? Let me tell you.
Early next year (Q1), when Playstation rolls out their exclusives: The Order: 1886, Bloodborne & MLB 15: The Show, Microsoft won't have anything to counter it, or at least has nothing announcend yet. I see this as a huge problem for Microsoft and Xbox One, because during these months, we will also see the release of these 3rd party games: Dying Light, Evolve, Resident Evil: Revelations 2, Final Fantasy Type-0, Project Cars & Battlefield: Hardline, all bound to sell better on Playstation 4 - judging by previous 3rd party releases.



- Obviously, one of these games stands out from the rest, Battlefield: Hardline.
This is a big one, and guess what, Playstation 4 has the marketing rights. Bundles incoming?

- Final Fantasy Type-0, which includes a demo of Final Fantasy XV.
That is likely to move a few consoles, or at least in Japan.

- And then we have the inevitable launch in China.


Will the percentage grow larger? I don't know, but there are good reasons to believe it will. 


So, going back to my initial question "can Microsoft counter PS4's Street Fighter V announcement?", Personally I don't believe they can.
I don't see how Microsoft could "moneyhat" a well-known 3rd party title and make it exclusive, while only having 36,13 % market share.
Sure, with Rise of the Tomb Raider they have shown, that they are able to get time-exclusivity deals in place, but for how long? If they keep losing market share.  

They're going to moneyhat GTA6, Fallout 4, Red Dead 3, and even Uncharted 4. I don't even know how that's possible.

Yes

You know, I have this feeling that BF Hardline will flop.

Actually, I think the Street Fighter announcement was to counter the Tomb Raider announcement.

Seriously where did you get 63% of market share from ? 

If countering with another fighting game then MS best chance is to get exclusive for Marvel vs. Capcom.

I would've said Tekken as well but that's already in the works for both platforms.

Why would they need to? If anything, Sony is the one countering MS after getting Tomb Raider.

If MS announces another 3rd party exclusive then it will most likely be something that was going to happen regardless if Sony had got Street Fight 5 or not.

Counter in what way? To address those who are on the fence between choosing a PS4 or Xbox one or those Xbox one fans who need something to counter on gaming forums?

By using math?