Tera didn't go P2W until after they went F2P. Most times you see a vanity only cash shop going into P2W is after a P2P game goes F2P. Otherwise most cash shops are already slightly P2W and just get horrendously worse; see any korean f2p like maplestory.
So until they drop the sub I wouldn't worry about it here. They'd also have to get dynamic stats or implement buff pots that last longer than 15 seconds for it to actually allow p2w to exist and we'll see that coming in advance.