They'll go for shale/coal/gas liquids and perhaps bioliquids. They have a large distribution infrastructure to exploit. BP is already in Solar and Shell is putting up windfarms. I doubt they'll be the top players in 50 years time, but they have resources, a talented pool of engineers and piles of money.
With a gun to my head I'd put my money on GE and the Silicon valley types to win through though.
But that they should go into power generation (wind, solar etc) except to greenwash is not reasonable. It's a completely different business.
Gaszprom might, as they have expressed interest in building nuclear reactors to reduce domestic demand for gas, so more can be exported to Germany (at greater profit as domestic prices are subsidized). But the reason German gas demand is increasing due to - that's right - nuclear phase out... Peak oil is not an energy crisis. It is a liquid fuel crisis.
Of the gas used in Germany, a mere 13% was used to generate electricity in 2004 ("Kraftwerke" = power plants), giving about 10% of production. The rest is used to heat over half of German homes and by the industry.
This alone renders your point moot, but I add to it.
From 2003, total German gas consumption stabilised at around 100 million cubic metre, or 3700 PJ, or just below 1000 TWh when expressed in heat energy production. So what might be the prime motivation to look for new sources?
Supply in 2006 (including (re)export!) was 36% from Russia, 26% from Norway, 20% from the Netherlands, 16% own production -- but production in the last three is set to reduce in the coming decades, with domestic production already in a steady fall. So make your guess.
But let's also look at the electricity market -- though it's not clearly separable, newer gas plants being co-generation (also distance heating). Gas power plants gave 11.6% of total production in 2006. That's now Less than all regeneratives combined. As for growth, let's start with 2001 (peak year for nuclear -- it reduced slightly from 171.3 to 167.4 TWh, one nuclear plant was shut down so far): brown and black coal also fell slightly, while gas grew by 18 TWh to 73.5 TWh -- and wind grew by 20 TWh. At the same time, the netto German electricity export grew from 1.3 TWh to 20.0 TWh. Now make the calculation... *Lunatic*, n. One whose delusions are out of fashion.
When nuclear is shut down (let's pretend for a second it will really happen) it must be replaced. Until just a few years ago everyone thought the replacement should be gas. Then Mr. Russian Gas was replaced by Merkel, all the gas conflicts ensued, oil prices went up, and voila! 26 new coal plants are to be built in Germany.
On top of that, using gas for heating is just... criminal. This noblest of fuels is wasted at producing heat, the lowest quality energy one can imagine, which can be produced in at least half a dozen other competitive ways. Peak oil is not an energy crisis. It is a liquid fuel crisis.
