No, it changes a lot for PvE realms because you'll get sharded/CRZed with only other PvP toggled players now, you won't be surrounded by unattackable folks now. You'll effectively be on a "pvp server" if you want to, without havin gto pay for it.

And as for people stuck on PvP servers not wanting to be there anymore "should have just played on a pve server", give me a break. Like it's that easy. Many people made these decisions many years ago before faction imbalances existed, or before they even knew what "world PvP" entalled" or before "world PvP" turned into "get 2 shot by a subt rogue before you can even react if you're not a tank/healer", or before they outgrew the "imma gank ppl and make them rage all day cause I get bullied in school xd" teen phase of their life and what not. Others only joined because their friends played there or other reasons. Once you have a few toons it becomes silly expensive to change your mind without losing characters you've invested a lot of time in.

Let people correct old mistakes without paying a $100, while you can still have fun with your wold PvP if you want.