How do you find David Attenborough's suggested solutions?

The best thing to do is watch the Netflix documentary My Life on Our Planet if you have Netflix and are interested or just watch the end from about 48:00 onwards, he describes two scenarios, scenario no.1 if everything continues unchanged as before and scenario No. 2 with the mentioned suggestions for improvement from about 56:00 onwards

I briefly list the proposed solutions for how sustainable resources could be used everywhere.

Increase the standard of living of all people in order to lower the birth rate
Use only sustainable energy sources such as sunlight, wind, water and geothermal energy (e.g. Solar parks in the desert, …)
Swap the tame for the wild. Giving back much more space for the wilderness to preserve nature and species protection and to stop climate change. Nature recovers and regulates itself if humans do not intervene and offer the freedom. Large nature reserves.
Predominantly vegan / vegetarian diet (completely abolish factory farming) effective use of space when growing fruit and vegetables, see the example of Holland.
Fishing-free zones in the sea, so that the fish stocks can recover sustainably and seas / coral reefs do not die.
Forests rich in species, stop clearing forests immediately.
Apply architecture. Plan living space, cities and vacation spots individually according to the available space so that trees are part of the house and are not felled. Shifting human life upward more to avoid roads, to allow rainwater to seep into the soil, and to allow wildlife to naturally fertilize and maintain the soil (roads prevent this).
Above-ground train traffic (express trains), above-ground cycle paths, gardens on roofs (see picture from the documentation)

Do you think that would work or do you think the economy and politics will not allow it at all?

That is completely utopian and only works in fairy tales.

It is really just a building of ideas, and that fails due to the lack of acceptance by the various governments.

Not to mention the difficulties in implementation!

This is the right way, but business and politics will not allow it. In our world everything is subordinate to consumption and at the moment the corporations have no reason to change that. That will only change when automation has advanced so far that consumption is no longer the engine of economic development. But even that will not necessarily lead to the better, at least not for the masses.

I don't assume that would work. It's a bit too utopian.

Using sustainable resources and nature reserves I don't find too utopian now

We think Attenborough's ideas are really great, but would (logically) also forego fishing / eating.

A vegan world offers more than enough for everyone.

http://www.PETA.de/Weltumwelttag-2019