You made a very good point about the rumour linking saliba to real madrid, because I believe that if the interest of real madrid became more serious, at some point, it would be very difficult for arsenal keep hold of his services for long, just as the saying that most players usually says, that when real Madrid comes calling, you can hardly say no as a player, so I believe that if real madrid became serious with their interest, at some point they will definitely sign him, but to the player, I think it's a wrong career move if he make such a move now, especially now that Antonio rudiger, David alaba and militao are still at the top of their game, because in as much as he is very good now, he is still not a better central back than any of this players I made mention off.
And as for the rumour circulating the internet of victor osimhen to Chelsea, I really don't know how credible is that news, but I believe that if the deal went through, it's definitely going to be a win win situation for all the parties involved, and he is definitely going to improve the attacking lineup of Chelsea no doubt.
That's something every player wants for UCL reasons, I believe that Saliba would want it for the same reason as well. That's why Real manage to get whatever player they want, they are the dream of any player because with Real Madrid, not only you are winning the league, but there is a chance that you could do the treble in any given season, while they didn't do it recently, it's a possibility. They win UCL fairly often and I think it looks like they may actually do it again this year as well.
That's why players like Mbappe goes there for free, and that's why if Real wants to get Saliba then they can get Saliba. Only exception could be Catalan players who may have some political reason not to go there at all.
I think it's quite clear that we are going to see Arsenal not be worried about it though, while Saliba is a great defender and helped them so far, they could ask Real to pay a huge fee, and Real is a rich club so they can pay that huge fee, meaning that Arsenal could use that money to get someone else easily, whoever would be their next Saliba. That's not good for consistency of the squad, but teams have players going and players coming every season so it is not really a shock for them.