Every year we're told it's our absolute last chance. Environmental brinkmanship hasn't work and the tune needs to be changed. Literally no economies are planning for mass famine or wars because no-one actually believes that is going to happen, except religious cults.
You are right that there is no absolute deadline. Now we are stuck with our hotter summers "forever". But we are not yet stuck with what comes next.
That is the problem exactly. We do not listen to scientists, because it's more convenient to ignore it. And when their models become reality, we'll just blame them for it, as they "knew" and did not prevent it.
Most, compared to all. And power plants are much more efficient at capturing energy than internal combustible engines. I see no real issues with the technology, just small kinks to be worked out, which is expected
Somewhere out in left field are the right things that need to be done.
2. Countries don't plan their economies half a century ahead. Most struggle to plan beyond the next election cycle.