The only thing we know with certainty is that we will have depleted fossil fuels if we continue to mine/drill and consume them at current rates. It is a finite resource, and we are consuming it rapdily.
The uncertaintly is what is the replacement technology, so it is hard to assess what to invest our money on. There are pros and cons for each of the potential replacements, and a big unknown is what mitigation will come to pass to overcome the cons.
So we WILL be ultimately doomed, unless we find a replacment...but which one?! Electric cars consuming electricity made with fossil fuels is NOT a solution.
The issue for digital cameras is not the question of 'doom' but merely ultimate contentment with a limited sized market, and who will survive and meet the needs of that limited market.
Phonographs were replaced largely by magnetic tape which was replaced by CDs which are now replaced by MP3 players...next decade what? The company that survives as a strong player changes with the technology when it comes along. We had the Beta vs. VHS wars, then the DVD wars and then the Bluetooth wars, the survivor moves past both wars to whatever is the newest.
The mirrorless vs. dSLR happens only to be the 'war' of the day...that question will be a moot point in the future, when something else will have displaced BOTH!