This is exactly my concern right now with my character that I’m lvling, basically with class selection.
My char is a lvl 36/12 Cryo C1 and I’m close to hit Rank 3, mainly I was going to pick Linker C2 and from there Chronomancer C3.
But my concern is that if I pick Linker C2 and then decide to get Linker C3 at Rank 8 when it comes out, then assuming the max Rank is lvl 10 I won’t be able to max the new classes to C3 meaning I’d lose the ability to get what it’s most likely going to be really nice abilities because of Linker.
In the other hand if I went with the standard build CryoC3-ChronoC3 then I wouldn’t have any problem since I’ll be free to max any new class to C3 with this build path.
That’s what I’m worried about this char, picking Linker would be good for the future with new classes that might come with shareable buffs that are really good and Lifeline later on with all those stats from more lvl cap might become a really nice tool to kill bosses in exchange of not being able to max any new class to C3 because you won’t have room for the Circles with Linker C3, which might be bad depending of how good the new support wizard classes that we get are.
If only I knew how many ranks there were, I wish it was 11 ranks, that way I can max Linker AND the new classes 
And in case I still follow the Linker Route I’m pretty unsure I’d reroll, basically considering it’s a full support class and I’m lvling alone most of the time…