Joshua lost already, Usyk did a good job, being the technical boxer and it seems that Joshua has a problem with fighter who move a lot and can box a lot. I also don't think that he underestimate Usyk, just a bad strategy by him and his trainer. And then they don't have any plan how to counter Usyk. If there is a British boxing mafia involved, it should be the other way around, Joshua should win in the judges score card, but that will be obvious. So yeah, why not Fury versus Usyk, but Joshua uses his rematch clause so it will be Usyk vs Joshua first and maybe the winner will face Fury for the unification.
I watched the replay of the fight several times and see what went wrong on Joshua, this loss is worse than the Ruiz fight, when he fought Ruiz he is a replacement for Miller he trained for Miller on his US debut but ends up fighting Ruiz instead where he has no idea what Ruiz is bringing, but on the Usyk fight he is well prepared and he has prepared for several months and he ends up getting beaten by a good and technical boxer, Joshua has no answer he prepared for Usyk but his plan did not work and he has no answer on Usyk attack, imagine several months of training yet he ends up not knowing what to do.
There's a rematch but what could Joshua possibly do to beat Usyk maybe change the whole team to a team that will bring Joshua's full potential.