The ideal room for HT is different (wider) than for audio. Square rooms are prone to be bass boomy.
Would you be using the same system for audio and HT?
IMO: Highly doable in the mid-fi range (say $2-4000 MSRP for the entire system). Audio and HT priorities differ enough to make it tough to have gear effectively doing double duty on high end systems. And too many compromises on the lower end to sacrifice quality for additional channels.
HT is a low priority to me, so I had a modest 2.1 combined system many years ago. Still have and love the Ascend Acoustics CBM-170 speakers (tuneful yet dynamic, image like absolute champs, horrible finish but super high content value). The Rotel receiver was a crappy build and a sonic dog. Cheaper Harmon Kardon and Sony receivers were/are way better.