Amorim's efforts are definitely not enough, I mean that with the players he has now it will be very difficult to do this, if we talk about the Europa League, and in the Premier League it will be impossible to change anything. To make Manchester United a team that can be in the upper part of the table, you need to change everything, you need a good goalkeeper, you need top forwards and defenders. Too much work to make any predictions now. Manchester United should try to win the Europa League, if they succeed then Amorim will definitely get good funding for transfers in the summer.
Manchester United's performance in the Premier League is quite bad. But I think right now they are not focused on the EPL and United have a goal to win the UEL. I think among the teams in the quarterfinals only Lazio and Bilbao will be tough opponents for United to win the title. I am not underestimating Lyon who are doing well in Ligue 1. But I think United will be able to eliminate Lyon and advance to the semifinals. So far United have never lost in the UEL and that is a good record. But if they want to compete better I think Amorim must make big changes in their squad. If they win the UEL then they will compete in the UCL and EPL next season. And they will not get good results with the current squad. I think Amorim needs to spend big in this transfer market.
Apparently Lyon this season is doing well in there league than Manchester united but it doesn't mean they will beat Manchester united in the Europa quarter finals and this is the only hope and opportunity Manchester united have to win a trophy this season and at same time qualify for the champions league next season. However, the 3 teams you mentioned are the major challenge Manchester will encounter in this Europa league and despite Tottenham Hotspur form, they always give Manchester united tough time and they have win Manchester united more this season and I guess last season too so they are also a treat.