Amorim has made his wishes known to the club recently that he needs funds to make player purchases. In an article I read he sent clear warning to the management of the club that if Anthony must leave there must be a good replacement for him. Honestly I think it is time for the club management to work in cooperation with Amorim to bring the change desired, Amorim is an ambitious coach and he looks to know what he wants and what he is doing, he should be given benefit of doubt and the finances to make that change happen.
A player leaves, another player can join and it is very normal demand for a head coach. Anthony has several seasons in Manchester United but failed, I can say he failed, to show his best and over years his contributions for them are very limited. If Amorim wants Anthony staying in the club, and has his plans to use this player, I am doubtful that he will succeed with Anthony. The player seems to reach his limit and can not contribute more for the club and perhaps it's better for all if they have agreement for his departure.
While I agree in most cases when "a player leaves, a player should join" type of mindset. However, we are talking about Antony here, not like he was contributing anything anyways. Which means that we are talking about a situation where there isn't really anything that should be replaced, hence they may not get anyone instead of Antony.
However, they should get some players, not because Antony left, but because the players they have right now aren't good enough and that's the only reason, if they keep playing with the same squad, I am sure that they will do fine, not great but just fine, but that's about it and I am not really seeing how things could change for them to get better, hence they do need better players. I specially look at the offense these days, defense has always been bad at United, for like nearly five years now and they still haven't fixed it, but nowadays even offense looks bad, they at least had a good offense during that time, maybe they should look into getting some wingers.