I use Google Fi outside the country and put the plan back in pause while I'm in the US. I'm very satisfied with them but don't trust Google enough to switch my main number.
Bingo! They could "sunset" Fi on a whim when they get bored. Plus Google's poor record of customer service or rather AI Bot customer service - is what will keep away me from trying it.
"Poor record" is actually not my experience. Customer service with Fi and Google Store is pretty excellent. A lot of people in my network also have the same good experience.
I've been on Fi for 4 years, and it has been a very flexible, positive experience vs. the alternatives at that time. Even if they were to sunset it, I don't particularly see the risk; I would just change to another service.
Fi customer service is actually excellent. First level support is actually knowledgeable and trying to help you, as opposed to just being a wall trying to prevent you from reaching second level support. Also the wait times have never been more than 2-3 minutes for me.