The company has promised to do whatever it can to "mitigate and resolve" problems as they come up. 

Like virtually every other internet-dependent firm, Epic doesn't have much choice but to patch Meltdown and accept slowdowns.  Even if it were in full control of Fortnite's cloud services, it wouldn't want to leave its systems vulnerable to serious attacks.  However, this suggests that online game providers (and really, online service providers as a whole) may have to scramble if they want to avoid connection problems and other headaches that come with servers suddenly stretched beyond their limits.