[Djonma]

I really don't know.
I've got to, and completed, Mission 8.
I do like the story of the ToA missions, it reveals a lot about Besieged and the way the Empire works.
They aren't difficult true, just require a bit of travelling and wandering around Aht Urhgan Whitegate, but this new expansion has besieged and assault to be difficult.
I'm sure that Mission 8 isn't all there is; the story isn't told, so I'm sure we'll be getting more juicy Missions in the future. It may be that they become more difficult, I'm not sure.