Considering they will release new jobs down the line that may have overlap with existing classes for prerequisites, it's not so left field to believe ARC can branch into both SMN and SCH. In XI SCH never sat well with me. I only got it to around 60 or so. I couldn't distinguish myself between BLM, WHM or RDM at all. I remember doing manaburns in the WotG zones and feeling terribly out of place. So if the pic is in fact SCH, I'll be on the fence about it until we hear more.
It's also possible that some of the jobs we're hoping for could come from a mix of jobs or even jobs and classes.
RDM = WHM + BLM + Gladiator lvl 30
BLU = WHM + BLM + Arcanist lvl 30
NIN = DRG + BLM + Archer lvl 30
GEO = BLM + Arcanist lvl 30 + Botanist lvl 40
The way they have it set up, there's a pretty staggering amount of options you could have. If someone has a calculator that does permutaions on it, maybe they could figure it out for us :)