Just a few thoughts:
1) I don't think Evolution works on big budgets. I think it is one of the studios similar to Sucker Punch and Insomniac where they are given a smaller budget to deliver projects as they aren't a studio that creates blockbuster games (in terms of sales). I wouldn't be surprised if DriveClub was made with a budget of £10-15 million.
2) Sales of DC will surely play a big role, especially since reviews are a mixed bag. So far from what I have gathered, everyone I know who has bought it including myself have loved the game. After Destiny reviews, I don't think Sony will be looking too much into reviews. Hopefully PS+ will drive sales.
3) A lot will come down to what the actual issues were with the servers and what could have been done to about it prior to release. I know there was a closed beta and they did say they tested it with thousands of players and it all held up.At the same time, if Evo are held to account, Sony should be equally held to account with the amount of downtime it has had recently along with sluggishness with its messaging service. I have had messaging coming through and disappearing and popping up an hour later.
4) I think the biggest thing will be how Evo continue to support this game. As great as it is I think Evo have not realised what they have created it. It plays like a brilliantly crafted racing MMO. All the different things that level up, that you can earn point for, how the unlocking system works, the clubs work, the challenges that can be made and how dynamic they are, they should have added various body kit parts (spoilers, exhuasts, sideskirts, widearches, alloys, back and front bumper, bonnets, roof vents, side view mirrors, tints, underglow and side vents) as visual upgrades that unlock as you level up.
They should have also ripped Forza's art customisation creator right off and added it so clubs can really make custom paint jobs on their cars.
Sony and Evolution are sitting on a gold mine and they just don't know it yet. If they continue to add things and flesh the game out, this will be possibly one strong franchise going forward, but that's if and how they pull this all off. I think the functionality upgrades should all come with a small cost attached (as it is better to get cars and tracks free).