The ponies have already been confirmed to be getting the ability to fly in 3.1 I believe? or at least they will fly at some point between now and 4.0 but they confirmed it ages ago.
I assume they will add new primal mounts at the same time as this seeing how the original ones didn't start with them either and I assume this is to pad out the longevity of the content by adding it later so you have a reason to go back instead of just farming it right from the start.

They should really rework sightseeing so that the original system can be used for something else maybe something to do with more in-depth lore telling and just have the old sightseeing work like HS so people aren't gated by waiting for the right time of weather at the right time of day that would make it much more accessible and people might bother to do it without a bigger carrot on a stick, as the barrier to entry on it is stupidly high for what it is.