Wolves Den !

[Nalien]

You're talking about splitting the queue even more which is adding more to the problem.

Which is exactly why I followed it up with Wolve's Den Roulette. Yes you'd have people split into different brackets, but a Roulette effectively gives players in a higher bracket reason to enter lower ones. A daily boost of PvP EXP and Wolf Marks, and a permanent boost to Wolf Marks for the in need bonus (or whatever rewards could be) should effectively counteract the negatives of splitting the queues into brackets.

Wolves' Den becoming popular again won't ruin Frontlines

Why would you bother queuing for Frontlines if Wolves' Den functioned though? Faster queues (requires 8 people instead of 24). Faster matches. More people would do Wolves' Den for ranking up and Wolf Marks and Frontlines queues would be worse than they currently are. It would be the opposite problem with have now; the majority would queue for Wolves' Den and the minority would queue for Frontlines, except the issue would be much worse for Frontlines given the numbers required. If it's taking people over 300 minutes to get into 4v4 matches when it's the less popular of the two, imagine the queues on 8v8v8 matches if the same were true for Frontlines.

especially if they eventually decide to get rid of GC restriction

I've posted elsewhere why I hope they'll never do that, and given the infrastructure around Frontlines I doubt they will. How would one go about "Guiding the Twin Adder to 100 Frontline victories" if Frontlines is reduced to Fangs verses Claws verses Other? The issue with Frontlines isn't that it is a static team based event, it's that they gave zero purpose to the teams. People generally join a team for a reason, and Grand Companies in Frontlines have no reason. They should attempt fixing that before gutting the content, in my opinion.