Hi Matador,
In theory, yes this could work, as long as you don’t have any other speakers. However, it isn’t ideal and I would suggest that there are much better options such as Beolab 7-1, 7-2 or 7-6 depending on the TV screen size.
Beolab 3500 is a very poor performer compared to other Beolab speakers of its era, with little bass output and treble that isn’t optimal for TV dialogue. Connection would be via Masterlink, so the speaker would only get a stereo downmix (not true front or centre channels). Control would rely on both the TV and the speaker receiving remote control signals at the same time, so some issues may arise when trying to operate it, change volume, etc.
Hope this helps!
Kind regards, Steve.