alt Hacker NewsThis is good analysis. The main longitudinal aspect omitted is that the profitability of the attack goes up as long as the price of BTC doesn't double or more each halving.
In ~6 more years, Bitcoin will undergo two more halvings, so if the price of BTC is not ~400k by then, then attack will have become more feasible.
In the near future every nation state will be vying for the largest stake of the BTC mining pie and the BTC race will be bigger than the Space Race and the Nuclear Arms Race combined and adjusted for inflation.