If could help DF even if Ishgardian is not the Mecenary GC.
Maps are all designed for 3 Factions, they won't change them all just to add a 4th, if they would add another GC the Frontlines will occur just among the first 3 GC who has 8 or 24 players in que.
As I already said and suggested in a lot of old post XD
An example of 2 consecutive FL, considering a lot of adders in que, low immortal flames:
Adders vs Mael vs Ishgard
Adders vs Mael vs Immortal flames
