This isn’t a problem facing just the PL though. It’s all intereconnected, like dominoes - if our Football calendar shifts, it’s likely the rest of europe’s will too. If the calendar shifts, then the transfer windows move in line with the new schedule. If the transfer windows move, short term contract extensions would be signed to carry through to the end of that period.
UEFA doesn’t require all leagues to start at the same time as several of it’s members, who have been regular participants of their tournaments (and even won it several times), operate in leagues that don’t run Aug-May. Russia is but one example.
I don’t know of one family who plan their trips around pre-season, but let’s go with your suggestion that there are loads who would be disillusioned by all this. They could still plan their pre-season trips, they’d just be doing it at a different time of the year, and only temporarily until the calendar shifted back to “normal”.
As per Wayne Rooney’s suggestion, If, due to a global crisis, a new Football calendar is forced to be created that see’s the current season end in October, purely hypothetically, then what would be so problematic with a transfer window commencing November 1st, a new season commencing in January and running to October 2021?
Follow that same path for the subsequent season and that means that the World Cup in Qatar could still safely be played as an end of season tournament, without any real jiggery pokery - call it a fortuitous scheduling happenstance.
Why would the other major leagues want to fall in line with the PL? What if some of them want to void their league?
Also, you say we should start Oct and finish July. What happens in June when Euro 2021 kicks off and half the league disappears?
FIFA don't give a wank about the PL and have already moved the competition one year so they sure as Hell won't shift a multi-nation hosted tournament out a few months, away from prime tourist time, to appease the PL.