My guess is that scholar would go in a very different direction from where it is in FFXI. Given that the grimoire is arcanist's weapon, scholar will likely be the second job (after summoner) for that class. This means that scholar will still have access to carbuncle in addition to whatever abilities scholar adds when you select the job.

My guess? Scholar allows you to pick job abilities from both thaumaturge and conjurer and then offers new spells that are different from both. If they wanted to go the FFXI path, those abilities might be helices or they might be the various strategems. Or it could be something completely new!