There are plenty of good alternatives out there. I tend to not use Google's DNS but I do run into it. I'd' have to do an audit and switch over the stragglers.

https://evilbit.de/dns-resolver-guide.html

How would it affect you if 8.8.8.8 service was terminated immediately?

I would not know. My firewall caches the root zone, talks directly to the tld servers and caches their responses.