A lot of this is now done, here's what remains...

Google Maps:
Provide OSM alternative and possibly Bing Maps alternative, sharing code where possible
If we rename main_google_map to main_map_users we'll need to update our "post your location" topic here to reference the new block name.

Google Translate:
Support multiple translation systems via hooks
Implement at least one other service
EDIT: Since done

Google Analytics:
Implement Piwik

Google Site Search:
Provide Bing Custom Search alternative

Google Chrome:
Write a sup_firefox_tools tutorial

I'm happy with this for now. We've scaled Google's influence back a fair bit, only preferencing where Google's products are radically better, or where Google is restricted to non-bundled-addons.

Google have now responded very positively to the concerns from Amp, partly due to pressure from me, but also many others.

Note Piwik is now called "Matomo Analytics". I tried it recently, it's a very nice product.
During using this I found (and checked) Google Analytics is currently considered illegal in Germany unless IP anonymisation is enabled (because of full IPs being exported to the USA) . This is based on their version of the GDPR legislation, so may also be found true in other European countries. EU users are therefore very likely to want to use a self-hosted version of Piwik as an alternative.