How confident can we be that nobody will crack a 128-bit key? In a context involving a block cipher like AES-128, excluding quantum computers, cryptanalytic breakthrough on AES and implementation attacks (poor TRNG, DPA..), and wrench, how confident can we be that by key search, "nobody will crack a 128-bit key" until 2100. Assume business as usual for humanity, use of 1 year worth of global production of electricity, 1 year worth of industrial production for the gear (used over a multi-year period).

Full disclosure: I'm trying to challenge my own half-baked opinion.

Updated: I leave it open if we allow multi-target attacks, where the same known plaintext is available enciphered under many random 128-bit keys. That makes a huge difference, but specifics of the block cipher become less important, which is good.

Note: we have a related question there; but it was considering a 256-bit key size, the methods adequate for that size need not be precise, and have not led to a definitive or even clear conclusion on 128-bit; plus answers are nearly 6 years old, and much more SHA-256 have been performed since then than I would have predicted at the time.

Note: We have another related question there at the 128-bit key level, but it restricts to currently available technology. Here, we must account for foreseeable technology more plausible than quantum computers usable for that cryptanalysis.

Note: 2100 and other limits have been set (instead of the original in the future of humanity as a species) for the sake of making a quantitative answer more falsifiable. Say, global apocalypse on that March 1 because a military subcontractor goofed on the leap year rule.
This question seems to be asking us how fast will computers grow. No cryptanalytic breakthrough and no quantum computing essentially means no attack faster than brute force.

So will humanity at some point in the future with significant resources be able to brute force 128 bit key?
I would answer, maybe. 256 bit key Almost definetly not.

Obviously predicting is hard especially the future but assuming humanity will not self destruct it will continue to progress and it is not unreasonable to assume it will come close to the limits of what is possible.

The main discussion on theoretical limits of brute force is in minim energy requirements. I suspect we may be short on physicists on crypto stack exchange so I will try.

Brute forcing a key requires enumerating the keys. And that requires changing bits. Each bit change erases some information and there is a minimal amount of energy required for that. Lauder's limit 
https://en.m.wikipedia.org/wiki/Landauer%27s_principle 

For brute forcing a 128 bit at room temperature this comes out 262.7 Twh(the annual electricity consumption of Spain) that is a lot But not something humanity can't achieve.  By lowering the temperature we can improve on this. And some say we could build another type of computer which doesn't erase information and this limit won't apply to it. Though such a computer might go against the spirit of the question which excluded quantom computers.

So we don't actually have any good theoretical limits to prevent humanity from brute forcing a 128 bit key eventually. Which leads to my answer. Maybe.

For 256 bits the same energy limit would put brute forcing well outside the realm of the possible.