Dunno
Here in NZ in the late 20's we began to identify a need for a substantial National Electricity Grid and the Ministry of Works engineers started thinking about it
Some of them started scouting rivers/elevations/locations/terrain. A couple went off to Mother England to look at dynamos and associated hardware
20 years and a lot of cock-ups later we had the Waitaki Dam in the South Island generating electricity. It has been a faithful servant for sixty years. So that's the first two lessons:
(one) Yes you can. And (two) good infrastructure will serve for a long time
(And, of course, once we had built Waitaki, the later Benmore and Aviemore and subsequent hydro plants were a snip - more or less)
On the other side of the world, in the US of A, folks were pumping oil out of the ground. But not with big, gigantic bloody things, but those mulitiudinous small rocker-arm reciprocating set-ups that have been working well since forever. That tells us that there's nothing wrong with "lots of small" either and maybe that weight-on-a-string-attached -to-a-dynamo thing could work in a backyard tower-sized setup? Who knows?
There's a bloke down here with a micro hydro that only puts out a couple of hundred watts. But, because it does it 24/7, it keeps his batteries topped up to the point where his solar gets a holiday a lot of the time
Also, of course, I suspect folks will have to learn to do more with less in the future. How many big-screen TVs does the average household need, anyway?