If more and more people enter cryonisation, there will be more and more of that capital that needs to find investment opportunities. Is it economically feasible to provide capital revenue for an ever growing amount of capital?

I think it depends on whether there are good ideas which haven't been funded, and whether the economic and social structure is such as to take advantage of the good ideas.

You might be interested in The Great Stagnation by Tyler Cowan-- as I understand it, he argues that economic grow has slowed in the developed countries (just the US?) because of a lack of good ideas.

I've heard the theory that the recent recession can be traced back to unduly low interest rates, which led to vast amounts of capital wandering the world searching for excessively high returns, and therefore vulnerable to scams.

Has someone really considered a society where the number of the "dead" equals the number of the living? Has someone considered a society where the number of the "dead" equals ten times the number of the living?

In science fiction, there's Why Call Them Back from Heaven? by Simak and Cryoburn by Bujold.