A price of $252,000 in era 0 (50 BTC/block) would have caused the Bitcoin network to attempt to consume about 30% of all the electrical power produced on the planet.
A price of $252,000 in this era, era 1 (25 BTC/block) would cause the Bitcoin network to attempt to consume about 15% of all the electrical power produced on the planet.
So, in order to keep the Bitcoin network from attempting to consume more than 1% of all the power produced we should all hope that the price does not reach that level until at least era 5 - about 2029 or so.
Of course all of these numbers are rough "back of the envelope"
estimates:
Original target Subsidy Est Fees Power % of total world
Era starting year BTC/block BTC/hour GW power production
--- --------------- ----------- ---------- ------ ----------------
0 2009 50.00000000 0.00000000 680.40 29.44%
1 2013 25.00000000 0.00000000 340.20 14.72%
2 2017 12.50000000 0.00000000 170.10 7.36%
3 2021 6.25000000 0.00000000 85.05 3.68%
4 2025 3.12500000 0.00000000 42.53 1.84%
5 2029 1.56250000 0.00000000 21.26 0.92%
6 2033 0.78125000 1.31250000 13.61 0.59%
7 2037 0.39062500 3.65625000 13.61 0.59%
8 2041 0.19531250 4.82812500 13.61 0.59%
9 2045 0.09765625 5.41406250 13.61 0.59%
Do you take into account that in the future we will be generating a lot more power, have lower power & better performing computers? or are you assuming we're generating the same power today as we will in 2045?