I think a few aspects to remember are appropriate here.
First of all, no one has taken the various FN tribal names out of contention. The simple reason for that is that, while we convene naming committees (to the extent that the government of the day gives them any say in the matter, which is the opposite of what has been done with the last two classes - namely the JSS/AOR named after War of 1812 battles and the AOPS named after alleged* Canadian naval heroes, both of which were determined by the Harper government to be the area of selection), there are no books, regulations, directives or guidance provided these committee.
Second, HMCS Haida is not available anymore. While not in commission, the last HMCS Haida is a National historic site, designated as such as it is the last existing Tribal class ship preserved as such on behalf of all the Commonwealth nations that operated destroyers of this class.
Third, I don't think that the name of the third AOR had ever been selected. I, in these forum, made a joke of the fact that if there was third one they could select Chrysler farm as the name, but it would be weird to have a ship named after a form of land occupation.
I tend to agree with FSTO: Single names for warships, though it can include compound ones, such as all the various Saints we have had in the past
. I mean, anyone ever calls HMCS VILLE DE QUEBEC by her full name? No. We all say either "the Quebec" or call her "the VDQ".
* I say "alleged" because, in at least one case, William Hall, we have a Nova Scotian born British Citizen who served only with the Royal Navy, mostly in and around India and got a VC for service to the Empire as a result, but well before Nova Scotia was ever considered part of Canada - but they had to find a way to include some visible minority in the mix, even though few if any such minority had ever served in the RCN at times of wars
fought by Canada. Similarly, Frederik Rolette, from Quebec city, who served with distinction throughout the War of 1812 but onboard British warships on the Great lakes - who at least came from a Canada - Lower Canada to be precise - was selected to have a token French Canadian in there somewhere, again even though few (but some did, especially in WWII) serve in the RCN's wars.