In my opinion, Bruno will play in Eriksen's position, while Mount will play behind Striker. Bruno will start the build-up of attacks from behind because Bruno is a typical playmaker so he is the one who flows the ball from the back to the front, while Mount will move freely behind the strikers looking for and opening space and has a high enough scoring instinct so he can score goals when the strikers experience stalemate to score a goal.
I like your analysis about the way they will play... But imagine a double CAM role for Mount and Bruno, with Casemiro being the sitting Dm!!! Because Bruno can score goals and assist well too and i am sure both CAM's track back enough!!! Lol... in my opinion the attack will cook and Manchester united will be so unpredictable moving forward!!!
Mount can play at many positions. You can play him as winger also but he won't be as effective as he is in central attacking midfielder role. It could be possible like Fernandes going a bit back on defensive midline but is given a right to be a bit aggressive and contribute with attacking moves also. But it would reduce the playing chances of Eriksen as well.
If you ask me I would say ten Haag would start Mount slowly into the matches and then perhaps as a winger later on as matches go by. I don't think that it will be two CAM's as it would really bring back United to their old form and has to cover a lot of ground in opponent counter-attacks. It would be really risky. Two DM's is fine as it is in my opinion.