There are roughly 780 million games sold on Steam alone, that's a massive amount and that's still not the entirety of the PC market, Steam alone represents roughly 75% of the PC digital market.
http://arstechnica.com/gaming/2014/04/introducing-steam-gauge-ars-reveals-steams-most-popular-games/





As for Dark Souls specifically... Should be higher than 300,000 copies sold by now.
http://www.gamespot.com/articles/dark-souls-pc-port-was-half-assed-says-director/1100-6406838/

The thing with PC gaming is legs, whenever a game is on sale, it hits the top of Steams sales charts, every single time, which can shift thousands of more units, over say... A decade that can certainly add up.

And overall, the PC is a much larger platform than all the next-generation systems combined and much larger than any single last generation console, currently.
And it's still growing.
http://pcgamingalliance.org/member-benefits/research/






Now, can a AAA game survive without the PC? Most certainly, can a AAA game survive without the consoles? Most certainly.
But if you wan't maximum profits, you need to support as many platforms as possible.

Depends what you mean. If devs went PC-only and actually made use of the specifics PC platform (return of the hot keys, mods, early access), used different business models (e.g. F2P, micro-transactions, user content support etc.) to get revenue rather than the broken blockbuster model, and a number of console gamers went the PC route, then revenue and certainly profit would go up.

If they just continued to released on PC and kept everything else the same as consoles now, then no.

Units sold isn't as relevant as revenue in this context. Without consoles or PC, AAA would undoubtedly downsize. Not to mention increased competition might drive vendors further, decreasing revenue overall. 

There wouldn't be hardly any AAA games if that happened and gaming would be extremely niche. I don't see most console gamers putting up with the PC's non-user friendly ecosystem. Hell, PCs are more user friendly now because of consoles, so I'd say the learning curve would be even more unattractive without consoles to lead the way.

EDIT: Now that I think about it. Arcades would most likely see a huge resurgance if consoles weren't in the picture.

I don't know if silly is fair.

There would be plenty of people who would find a way to continue playing hard core (high graphical fidelity) games - and that would mean PC. But plenty of people would also just fade away! 

Well, look at how pc only AAA franchises are doing. Flight simulator gone, Age of empires gone, Sim city might as well be gone.

Without consoles more people will game on PC, however games would be more geared towards the average Steam pc, which is dual core cpu, Intel HD graphics and 1mb vram. If you think consoles are holding pc gaming back, wait and see what happens without them...

I can't say I agree. The hardcore gamer may be an addict, but the vast majority of the gaming population is not. And how many "hardcore" gamers would never have been created in the past few years without console gaming, I wonder?

It is possible but it could be a blessing in disguise. Losing the couch market would cut down on a lot of this "me too" AAA stuff that the industry spews out and clouds the marketplace with. Last time I checked recent COD games sell like shit on PC which alone could be worth the switch... :)

True.  And I am not throwing stones.  I am not a hardcore PC gamer but I do spend a lot of time PC gaming.

I just think its most reasonable to expect that whatever PC gains from the departure of consoles, it could lose more from the shrinking of the market to make games for overall.

I don't think you're seeing the full PC gaming picture with statements like that.

PC gamers today is the most diverse bunch of types of gamers you will find on any platform at any point and time. The console gamers may consider themselves as hardcore or casuals but on the PC you will find every type of gamer and the diversity of gaming found on the platform reflects it.

I guess to slightly revise my answer above, there would be absolutely no need for "AAA gaming" hype based gaming as we know it if consoles were to go away. Games wouldn't have to have massive first week sales to recover marketing budgets, packaging, storing and shipping costs. Everything could just coexist, and good games would sell and keep selling while bad games would die an immediate and painful death.

People tend to forget that PC was the platform for high budget titles until about 2007. DOOM 3, Neverwinter Nights, Halflife 2, FEAR, Crysis were all PC first cutting edge games that we would call "AAA" today.