One option would have been to stay small. Keep the yearly spend down where it was in 2010, don't hire too many more people, and save all the donation money they brought in. Build that fund in the good years to pay for salaries in the lean years.
There are a lot of things to criticize about Wikipedia but lack of financial planning probably isn't top of the list.
And what are the realistic chances of that actually sticking long term?
Same chance as corporations and governments keeping spending, corruption and cronyism under control long term. So, virtually zero.