If I remember well I read on a traduction from an interview (do not remember which one sorry ><) that poetics will still be capped after heavensward since ilvl130 will be still powerful during leveling.

That's why they do not plan to remove it for now.

And do no forget that there will be players who will not buy the expansion so they may stay with our two currents currencies where the others will get in addition the new currencies.