The current economic circumstances we observe in football will not unavoidably lead to a burst of the bubble.
Generally speaking, as long as there is technical progress and population growth, there is organic and sustainable economic growth.
Bubble growth (i.e. unsustainable growth) only occurs if the target area is inundated with more money (i.e. stored up economic activity) at a time than it can organically absorb (i.e. has immediate and sustainable outlets ready for the money to go). If this doesn’t happen, we see a rapid and steep increase of price levels (=> price inflation).
If a bubble situation has arisen (i.e. prices for goods and services in a given economic system have skyrocketed due to a lack of organic absorptive capacity of the system), the bubble will only burst if the source of money suddenly dries up and thus no more money is put into a system that depends on its constant supply for its continued existence.
The risk of money drying up is especially great if all or most of it comes from a single source.
Economic growth in football has been rapid and sharp and the fact that player transfer fees and salaries have been soaring in recent years indicates a situation of bubble growth. All the money coming in can’t be converted into more sustainable targets quickly enough (youth academies, new stadia, other kinds of infrastructure, second or third teams, other sports, dividends for investors and so on).
But is the bubble going to burst? As I’ve said, this risk would be especially great if all or most of the money that’s flooding football came from a single source AND this source would show early signs of a potential depletion.
Neither is the case in football. For one, a football club’s sources of revenue are diversified across several income classes. These are commercial income, TV/media rights income, and matchday income. Income from all of these revenue classes has been steadily growing probably for as long as professional football has existed, slowly at first, much quicker now.
Secondly, there is no one single income class that dominates and outstrips the others. Neither media rights nor commercial income nor matchday income alone makes up the lion’s share of a club’s income.
In some markets, especially England, TV and media rights revenues have been rising faster than the other income classes. So you could argue that perhaps we see early signs of a bubble threatening to burst. But so far, most media rights income has been domestic income while foreign markets income has been very laggard and almost negligible by comparison.
As the population of Britain is only 65m compared to a world population of 8,000m, it seems reasonable to assume that as long as football as a spectator sport is growing worldwide - and there are HUGE underdeveloped markets still left to conquer (esp. Asia and the US) - there is still more than enough room for TV/media revenue growth abroad even if domestic markets should stall.
Income from all the other revenue classes has been growing much more organically and sustainably. The same as for TV/media rights, there is no reason why commercial income (merchandising, sponsoring, advertising etc.) should taper off and not continue to rise. The more spectators around the world, the greater the markets not just for TV rights but also for merchandising and advertising.
To conclude, yes, there are clear indications that football has entered a stage of bubble growth, but catastrophic events aside, there are no definite reasons why its supply of money (or even the growth thereof) should come to a sudden end.