Capitalism does not require growth at all, and will work fine in a shrinking economy. Fractional reserve banking, that uses a currency that is debt to be paid back to private bankers, requires that growth, to not fall apart. Capitalism is basically just taking the power to invest and use property from certain classes to anyone, with social contracts and legal frameworks supporting that (including the right to say no, which, FI, is violated by property taxes).

It's going to end, not for lack of growth, but because too many people are going to too stupid and/or poorly raised to handle basic day to day responsibilities on their own, and self-organize. The typical citizen being able to make informed decisions around their labor, money, and wealth, are implicitly necessary, along with being willing to sacrifice time/labor for the good of the whole.