Unless I'm very much mistaken Ink of the Sea is still required to make 117 different glyphs, according to Wowhead.
Those inks are going to be harder to obtain due to the whole supply and demand thing with the supply of the Northrend herbs required to mill them eventually dwindling.
You could of course trade in the new Blackfallow Inks for them come 7th Dec but I imagine those will be even more expensive at the start of the X-pack.
What I did shortly before Shattering was kept a quarter of mine and traded the rest in for a variety of the lesser inks to keep the old Glyph shop running.
With the new race/class combos and Worgen/Gobbos inbound there will be lots of alts and new mains all wanting those glyphs.