Everything you're stating is driven by wild assumptions that seem to be based on nothing except for trying to paint a pessimistic picture as possible. Everything would be contingent on a huge variety of variables - the algorithm, the usage, whether we think of a unified crypto or software specific coins, and much more. The idea is not to go for another VC hype bubble aiming for 80 billion percent growth or bust, but simply to create a stable source of revenue that companies can use to sustain themselves without resorting to the increasingly broken 'ecosystem' we have in digital rent seeking/advertising today.
This is really quite a perfect application for cryptoes where everybody could win, but there are a number of not yet solved problems that need to be overcome. One issue with this idea, and as with all good decentralized ideas, is that the person who does ultimately create it would likely receive little reward for it. It's not about making money, but about improving the state of software as a whole. There are only so many Tim Berners-Lees.
Not when you include performance in the "consumer friendliness" side. Existing software is already way too bloated and keeps assuming it's the only thing users run; cryptomining would only exacerbate that effect. Especially that to earn a measurable amount of money over the lifetime of the product, your typical chat app using this model would have to run CPU and GPU at 100% load.