Could you explain why you think mining companies will fail? Miners should always, on average, be profitable. If mining becomes unprofitable for some, those with a low profit margin will be forced out, but those with a safer profit margin will be able to stay in and make profits.
I believe mining is in an extended bubble. Mining companies will become forced out by ASIC and low-energy mining.
The majority of successful bitcoin companies are private and dont offer shares to the public they can buy.
A company that can raise money has the ability to be successful. Many large companies are public.