If I follow you, when Bitcoin mining will become unenomic, Bitcoin will surely die ? In 2050 or 2060, when there will have not a lot of Bitcoin mined at each block, no one will mine it because everyone, even the one that have free electricity will lose money. But maybe people will mine just to make the Bitcoin network work, like some are already doing by running Bitcoin nodes.
There are miners out there with access to free electricity or very, very cheap electricity. Those will still be in profit just fine whereas other current players will have to throw in the towel unless they can find a similar set up. That's a tough thing to find.
Most assume that transaction fees will make up for the block reward in the far future. That makes sense if it catches on and succeeds and there are far more users than there are now. I think at present fees are often 0.2 BTC per block or less. If it doesn't then mining it will become increasingly thankless as the block reward diminishes further. There'd come a point where it's only mined for altruistic reasons which most people aren't going to consider.
In a really far futur, when the block reward will be less than 1 BTC, no one will profit, since the price of the ASIC will never be recovered, even with free electricity.
Erkallys, you don't think transaction fees will increase enough to compensate for the reduction in the block reward? (Gentlemand, you also seem sceptical - or at least not totally convinced. I've always taken it as a given, without giving it too much thought, that TX fees would be subject to market forces. I'd be interested in having my assumption challenged).
