Yes, everything being sold at Eulmore right now for tomestones will be sold for poetics in 4 months time. This is what they always do so I don't expect it to be any different this time.

If it's like previous expansions, you will be able to buy item level 515 gear from The Crystarium. You will get high-quality item level 515 gear from the Main Story Quest before the first dungeon of the expansion.