Some people seem to be forgetting about what economists call elasticity of demand.
The family flying off for a 4 day half term break to Spain could quite happily make do with driving from their home to a beach for 4 days instead if the air fare looks too high - I doubt most people on this forum over the age of about 25 had many half term trips while they were kids to Mallorca, unless their parents were wealthy or they had family ties.
The large company trying to close a deal that would give a profit of tens of thousands is far less concerned about an air fare costing an extra 100 pounds compared to what they paid 10 years ago. Furthermore, businesses tend to be in the centres of major cities - not really FR's business model at the moment.
In addition, the duty of care placed on employers, and Ryanair's refusal to integrate with business travel agents' systems (no, I'm not talking about the HIgh Street chains) means that apart from niche routes and the risk of being mucked around (explaining to a potential client that Ryanair will put you on the next flight in 3 days time is not remotely plausible) makes companies of 100+ employees wary of Ryanair
Very little business travel will go Ryanair in the next 5 years. Yes, Ryanair could capture some of the market, but it will require substantial investment in systems, customer service and marketing, all of which take time. Easyjet can capture some of this business, but the rest remains with legacy carriers. If oil shoots up, business travel will largely go on - even if some goes to video conferencing.
Private individuals will find a way to keep their bills down. If rising oil prices mean that the weekly supermarket bill goes up, then while the annual family holiday will be preserved, those weekend trips to somewhere 2 hours flight away will get cut.