Just my personal thoughts on the oil industry
Your idea on planes isn't bad, but it misses some of the important elements of flight. Large-scale gliders are pretty impractical for jumbo jets, due to the downward pressure exerted by passenger weight, cargo, and mechanics/electronics. The solar panels are good for power generation, but jets also require significant power reserves, more than can be stored in practical batteries. Also, solar power reliance would render red-eye flights inoperable. Reducing the number of planes in the air is, as current, contradictory to market demand - the fact is, people are doing a lot of flying these days. Most importantly, the vast majority of fuel use occurs during takeoff, and as it stands right now, fossil fuels are the only reliable source of that kind of power. The biggest problem is, aviation has absolutely no room for error, especially given the large quantity of human elements involved (specifically, the entire passenger roster on your average 747). Without sufficient regulatory pressure, it's not economically sound to pursue alternative approaches to aviation yet, due to insurance, inventory, and R&D costs. I'm hopeful that the time will come soon - I'm wondering if miniaturization of nuclear fuel will contribute to cleaner air travel. It's my belief that eventually, demand is going to outweigh distaste, and nuclear power will become the primary driver for civilization for the next hundred or so years, barring extremely significant breakthroughs in emerging fields.