Its not all doom and gloom. Yes, EPL clubs have been growing revenues, but even they will have a cap at some point. Global & local fans bases dictate the revenues of the future. Even now, the top 3 clubs in terms of revenue are Barca, Real and Bayern (as per Deloitte 2019-20). Top clubs in big nations like Spain, Germany and Italy will always be up there, and hence will always be good investments. I don't think the growing power of EPL clubs will necessarily change that.
In terms of future, we could also argue that while EPL is close to maximising their revenues due to great marketing and product in the last 20 years, top clubs in countries like Italy have a big opportunity to optimise revenues. Clubs like Juve, Inter, Milan have a strong local market, which provides them with a good base to build upon. Once clubs in Italy invest in better product (stadiums, pitches, commentary, etc) and focus more on marketing, there may be a bigger opportunity here to increase % revenues. I say % revenues, not total revenues, from a ROI point of view. That makes these clubs always attractive to a big investor.
So this can be taken both ways. EPL clubs are more attractive now, but top euro clubs will always be an attractive proposition. I don't believe these PIF rumours. But hopefully soon someone will want to buy Inter from Suning, it can't happen fast enough as far as I am concerned.