What I've said above is of course anecdotal based on my circle's and my own experience, but when looking I was never without a new contract longer than a couple of weeks in the last 7 years. The next 10 years... I don't know, however another advantage being a contractor in my opinion is that you have more opportunity to be exposed to and learn new stuff, which helps staying current.
London. Agreed, next 10 years who knows. 7 years is interesting because it's just not long enough.
Pre 2008 I was surrounded by contractors all citing the benefits of the extra money. Then things thinned out. I remember one day looking up and I was sat with loads of empty seats around me and I realised just how many contractors they had let go over a period of time.
Contractors have also been first to be let go. The last 10 years, yes. The next 10, not so sure.