Guild Wars 2

It just strikes me odd that it’s an update that’s not mandatory for everyone. so some areas and maps will be exclusive for Heart of thorns buyers?
I’m a bit confused about how it works.

I’ve been wanting to come back to play guild wars 2 and i’ve been wondering what is the states of the servers and the numbers of people playing.
Post your thoughts/discontents of this game if you’d like as well.
Also been wondering if the upcoming update is required to be purchased seperately? if so, how much would I have to pay if I’ve already purchased the pre-ordered original guild wars (deluxe version)

Thanks a lot.