There is no engine limit, supplying three other teams is allowed without FIA permission, with FIA permission there is no limit and ultimately there isn't much reason for the FIA to deny it. If Renault are incapable of making a decent engine then it's better for the sport that more teams have competitive engines.
Considering people are banging on about using regulations to even up the field, well, here you go this is the perfect way. You can remove the 'limits' on engine regulation but that doesn't automatically mean someone will get it right. Merc got the current engine regs done right, 3 other teams at their first attempt haven't, Ferrari got it closer to right after a further year, Renault went backwards rather than forwards. This is all aside from the fact pretty much the whole engine is open to updates through reliability improvements and tokens don't have much scope on what you can and can't do. So one way you could say hey, Renault have 30 more tokens.... but they could screw up the upgrades and make a worse engine or one only marginally better. The other option is to say, how about we just let more teams have a Mercedes engine, that way we already know the outcome, more teams on the same power level engine wise.
As such it isn't remotely dependent on the Lotus deal. It's also, rather weirdly, been said that Renault buying Lotus was also looking like the end of Renault engines for RBR and TR, and that if they got the deal done soon it would still be expected Lotus would use Mercedes engines in 2016. It would give Renault a year to ignore on track engine development, stop working with 2 teams and trying to fix on going week to week problems. It would free up a lot of time to focus on making a new engine rather than rushing to get one done sooner and then having to find ways to improve that engine all year.
Could we see RBR go Merc, TR go Merc or Ferrari, no Renault at all next year(except in branding on the Lotus car) then in 2017 Renault bring an engine and... well, we see if it's any good at all.
If 2016 has no Renault engines and everyone except Mclaren on Ferrari or Merc engines it would be a significantly better season.