Personally I have mixed feelings.
I think there'll be all the pressure in the world on all PSG players, whether Messi signs for them or not, and the manager who has only been to CL final but hasn't really decisively outplayed or beaten any of the current big players in Europe. Subjective measure of success goes out the window if they keep Mbappe and sign Leo, especially now they have Hakimi and Donnarumma in goal - if anything goes wrong, it'll be big drama and automatic scapegoating more than before. I even think Messi is likely to not be that comfortable in a different place, especially at that age. If he doesn't sign, the side is still flawed and IMO just as likely to spontaneously combust over previous problems (Neymar and Ramos injuries, Mbappe and Icardi headcases). I know Ligue 1 is having big issues with Mediapro deal potentially forcing them to sell a lot, but I dont think better competitors has ever been what made PSG underachieve anyway. [MENTION=15570]Newcomer[/MENTION] or [MENTION=23081]Bulgroz[/MENTION] can attest to it more I imagine.
I've seen stranger things in sport and while there'll be ton of bad press on Barca seniors and they're not going to get any better, I somehow think that if Koeman manages to use the lack of Messi to actually get team behind achieve consistently good scores in key moments, it'll be a successful year, far more than anyone would have bargained for. Depay, Pedri, Fati and maybe likes of Dest benefit most from having to be subject to an established order and preconceived notions on offense. It sounds like contrarianism, but I do genuinely think that Messi stifled progress and independence spirit in any side he's been in. May be wrong, but I do expect it to be a better year than folk think.