I doubt it's going completely dark any time soon. They probably have enough money to keep trying the subscription model at a loss for a while (read: at least a year). Furthermore, in the case they do not have enough paid subscriptions, I suspect they will save face and minimize operating cost instead of changing their revenue model again. According to facebook comments from them, they did get more paid subscriptions in the beginning than they estimated, so they do have some liquidity.
But in the unlikely scenario that /DRIVE were to disappear completely, I seriously doubt any of the crew would have to look very hard for a new job. With the success of Chris Harris, Matt Farah and Mike Musto videos, those three would absolutely get a another job on another show. Maybe on a new media channel like Motortrend, maybe on network TV. The production crew of /DRIVE is probably hired help these days so they would just swap projects.
/DRIVE has been more of a sideproject for most of the guys there. Chris Harris is mostly a columnist for newspapers, Matt Farah has SmokingTire, Mike Musto is apparently an instructor / organizer of some sort, Larry runs AMMO, Mike Spinelli is a hardcore journalist, J.F. Musial owns TangentVector and is a producer for advertising, etc. All the guys have something that would generate some personal income while they looked for a new sidejob / passion project. It actually seems like a pretty good lifestyle, as opposed to Youtube gamers for example, who usually have nothing except their gaming channel, and rely on existing long enough to be noticed by gaming-related companies (manufacturers, game publishers, content networks, etc).
So yeah, probably no reason to fear for the guys livelihoods. Chris Harris specifically can just start his own channel and it would instantly have tens if not hundreds of thousands of views.