Well, making a whole set of new levels (probably partially inspired by the original ones) with a linear progression is something doable, imo. It will pretty much be Hexen classes, enemies and weapons in Heretic(-like) maps. You may as well just play with
this wad then.
On another note, I think this idea of yours should've been posted
here, just saying. Users share ideas there all the time. While I don't think this hubless concept is inherently bad, keep in mind that a lot of people feel that the main identity of Hexen gameplay is precisely the hub system, tho.
