Long story short I left the game a little before a month after Mists came out due to a variety of reasons but mostly the (at the time) crazy rep grind and the fact my guild broke apart and had a lot of problems in MSV. I went to Rift when Storm Legion came out and haven't looked back since, but I've considered coming back to WoW, although I'm no fan of the cumbersome grind they added.
Now my question is this: As I understand it for Mists they aren't doing the Wrath/Cata model of a new tier coming out and invalidating the prior tier's gear (not saying that's a bad thing). Would this mean if I came back, I would have to find a... how shall I say... low caliber guild that was still in T14 and clear that before having to guild hop into a guild working on T15? Or is Heroics -> T14 LFR -> T15 LFR enough to prepare you for T15? To put things in perspective when I left the game Heart of Fear/Terrace had just come out into LFR (I didn't run either of them before leaving; I ran the first part of MSV I think twice in LFR, and killed Stone Guard once on normal before the guild had problems and broke up). In short what would be the progression path for someone who left the game shortly after Mists launched and has barely touched T14?
I didn't play during TBC, and in Wrath and Cata of course if you took an extended break you could gear up via badges/points and jump right back into the current tier. With that having changed, is it encouraging guild hopping and using low progress guilds as stepping stones to get into high progress guilds (granted that happened before, but the stories I've heard from TBC state this was a major thing going on then)?