Either they will disable follow in /pvp or they will only enable follow to work fully in world pvp. You can 100% expect it will be disabled in Bg's. Dunno, I'd really like to see it in world pvp given that resource farming in Vanilla is not worth of boxing (herbalism,mining) and then given that it's pvp realm with only limited people (no sharding presumably at higher levels (20+) ) you would constantly have to fight your way through organized groups. Also, given security today and as I've said limited pvp realms any cheater/botter would be spotted on sight, through entire classic span.

We'll just have to wait and see. I do hope I get beta access at least on 2 accounts (dunno if it's on bnet account or for only single licence) so I can test it out.
Would be amazing to have follow work in pvp as in my opinion in Classic it will not hurt anyone ( we are not that many nowdays anymore). Hope that Isboxer will be enabled shortly after beta is out (addon mainly). I do really like Mirai's warlock setup on demo so most likely I'll run either that or warriors (don't forget we can counter mages with FAP (pop FAP before 35 yards) (charge with 3 warriors,intercept>dead mage)).

I think mostly the boxer strength will be mainly warlock/ele setup,especially shields/and shield from AQ (I've explained that to Kruschpak way before). You can implore tactics such as 15x dot in 3 globals plus 4x seduce/4x coil/4x shadowburn even without follow. Especially if you are running UD warlock (which it tbh our only issue with 5+ groups).