Don't worry too much about becoming obsolete. Frontend web development is my field and it moves faster than any other single area of programming. I took 5 years off due to burnout and it only took me a month or two to get back up to speed from a technical perspective. Putting up with the bullshit interviews is another story. I freelance now.
+1 for freelancing. I never had to deal with any of the bullshit 2 days on-site interview with whiteboard challenge. I don't get the full interview routine because I'm considered "external" and "temporary workforce" ( 6-12 months ). Funny story that I've seen lots of "internals" moving to other gigs in about the same amount of time.
Freelancing gives you the opportunity to do your job, get your money and don't get involved in company policies. As a side-effect you pass interviews and have flexible working hours.
How do you start finding clients for freelancing? How do you figure out a competitive rate without going too high or low?
I have about 10-15 hours of real work to do each week at MegaCorp. The rest is idle time at my desk/couch. Thought about moonlighting and doing 2 jobs but freelance sounds better.