I'm still a bit of a spring chicken compared to you, but my biggest stumbling block (at least in the relatively tiny technical job market where I live) is that

I'm still a bit of a spring chicken compared to you, but my biggest stumbling block (at least in the relatively tiny technical job market where I live) is that interesting generalist jobs don't pay as well as older (i.e. not just out of college) employees are used to. The high pay is restricted to employees of big, boring companies and the occasional startup that wants to hire a guru in some very specific narrow field. That's not a problem in itself, but as one becomes accustomed to a higher salary, one's expenses tend to grow correspondingly: creature comforts have a way of turning into necessities, possessions accumulate in way that makes a smaller living space impractical, and dependents and stakeholders multiply. So to the extent that you're competing on price with low-expenses no-family just-out-of-college folks, you're at a disadvantage. You need to make and keep yourself valuable in the other areas employers might look at.