I think given how long the Summoner has had a book, its highly unlikely to change now. That said, I wouldn't be opposed to them using paper talismans or paper scrolls as a variance to the book. The summoner doesn't change how they summon the primal vs Carbuncle. Its still imbuing via special ink with the summoner just using attuned aether and their "idea" of what the summon should look like. Essentially I think book does fit in the context of FFXIV even if i wish it didn't. One thing i would like is the for there to be more options than just book - stone tablets being another as mentioned by Teno.

I guess the issue is that the animations are very attuned to them holding the weapon in a specific way so would need to be moved. That said, another weapon i did like the idea of was for crystal focus/ book/scroll to float beside the summoner or for Carbuncle to be the weapon we use.

Either way, i doubt we'll see any changes yet if ever.