Anyone hiring people for specific things they learned in University is doing absolutely the wrong thing.
Many high end schools don't even have very rigorous applied computing standards, meaning, they might have some hardcore CS stuff, but they don't necessarily encourage good programming habits, patterns, culture etc..
So the education I think always counts for a lot, it's the work experience from 30 years ago that actually may be less relevant.
One opportunity might be to find something 'related' - for example, writing documentation, doing sales support, technical product management - basically anything but front-line engineering. There are a lot of such jobs.
Do you reach out for weekend lunch dates just to chat? Are people open to that (given work, hobbies, kids, etc.)? I'm having a hard time coming with "excuses" and serendipity to stay in touch with people I'm no longer working with.
This is not necessarily about ex-coworkers.
In general, weekend time is more guarded and precious so try to meet for a coffee/drink after work. Or you can both go to an event that is related to mutual interest (tech is possible but would not recommend it). Trying to meet more than one person at the same time also leads to scheduling difficulties.
If you want to meet up with more than one person, consider hosting a Tuesday night dinner party. Nothing fancy, do take out if you can't cook that well. Tuesday night is usually an "off" night for most people.
Ideally, you meet with people you would like to stay in touch about every 3 months. A person is not really in your direct network unless they know who you are and can recognize you in person and know what you are currently working on and have seen you in about the last 3 months. But here's the catch, you don't necessarily have to be directly in contact with everyone. A simple "How is Jane doing? Have you heard from her" can keep you updated enough.
There are some people from work that you might think you'll remain friends with after leaving with whom you do not meetup with again. That is ok. People drift off. Maybe it was just the recurring coincidence of time, location, and possibly purpose (going to the office for years) that made you "friends".
Like the saying goes:
Friends for a lifetime
Friends for a reason
Friends for a season.
The most naturally extroverted individuals that I know have many social circles. One friend I know always buys two tickets to a performance and never lets the other person pay for it.
Finally true friends whom are hard to find are those who you can open up and be vulnerable with.
Facebook has bastardized the term friend. Not everyone is going to be your friend, as it requires reciprocity and shared caring.
Literally, that's what I will send to one of my ex-coworkers, or vice versa. It's not anything more than that. Either through gChat or Facebook Messenger, I don't find it that hard, and I don't feel like I need excuses.
I recently went to a going-away/layoff party for one of the first engineers I worked under in Silicon Valley, 20+ years ago. I hadn't personally talked to him in 10+ years, but he was delighted to see me. We shared war stories about our old company, dot com bust, etc. It was great, and doesn't have to be anything more than that.
That and we're always bouncing news, advice, and helping one another in said Slack instance. Safety in numbers.
Edit: the other thing I do is pass along interesting looking recruiting emails to people who I know are more on the market than I am. I figure they'll do the same for me next time I'm ready to move on.
Yeah this is an important thing everyone should be doing. I used to be shy about this but everyone is in the same boat and most do appreciate a quick drink or meal every few years to network, even if you're not friends.
Two of those degrees (MS and PhD) are graduate degrees, not undergrad.
In the specific case of AI, the field has changed massively over the last 10-15 years, so the field-specific knowledge conveyed by degrees further back than that may indeed have depreciated quite a bit.
However, field specific knowledge is not necessarily what makes graduate degrees valuable. It's knowing that you're getting a candidate who knows how to branch out into unknown territory, who knows how to research the relevant literature, who didn't quit when the going got tough, and who can express themselves in comprehensible prose. These qualities don't become irrelevant, even if Isaac Newton was your PhD advisor.
Not saying it should be that way but I bet some people will think a >60 year old may just look to hang around/coast for a few years waiting for retirement.
What modern technologies have you recently worked with? What does your resume show, 20 years at the same company, or do you have experience at well-known, "prestigous" companies like FANG? Are you pigeon-holed into a specific area, or are you a generic, back-end or front-end expert that has worked in relevant and useful technologies for 2018?
Also, with 35 years of experience in Silicon Valley, don't you have a network of former coworkers that you can contact for references or jobs?
I'm 50 years old, and I've had no problems getting jobs and recruiters from FANG won't stop contacting me even now. Sure, things might change over the next few years, but I also have a rolodex (old man's terminology) of former coworkers that I routinely have lunch with still and can ask for jobs, etc. I'm sure things will change, but I'm also doing my best to ensure that I can retire in the next 10 years as well.