I'm in my early 40s, computer programmer, and I've temporarily lost access to my WhatsApp account because I don't have a recent enough mobile phone, and the phone that I do have doesn't have a relatively recent OS installed.

It's a 4-year old (I think I've got it for 4 years) iPhone SE, on which I never updated the OS because I hadn't feel the need to do it. When I started getting pop-ups that "hey, our app will stop functioning on your phone unless you upgrade the OS" was already too late for that, I was afraid that upgrading the phone to the latest OS will cripple it permanently in terms of performance (the battery is already on its way out by this point).

So, assuming I get to 70, in no way I'll be up to date by then in terms of having the latest OS installed and all that crazy stuff, who has the time and the nerves for that? (especially the nerves).

The DMV works with people like this all the time; perhaps something could be done there where you have a government issued email address that you can't lose or be locked out of (worst case you take your ID to the DMV and the nice clerk helps you reset your password/sign in).