Will most of ARR and HW mounts become irrelevant in 4.0 because they can't swim? Apparently there will be large underwater areas which will be accessible only with a few new or maybe some upgraded old mounts.

If ARR to HW transition is any indication, the vast majority of them like beast tribe and tank mounts are useless in HW areas because they can't fly. A few selected mounts like Kirin got an ability to fly, but that was like 1 mount upgrade per patch.

Will all these ridiculous bird farms be for naught like it happened to primal ponies? The only use for them now is to take a rare ride in ARR areas or afk in Idylshire.