I had a SailfishOS phone for four years; an Xperia XA2+. The operating system was wonderful, and being able to run Android apps when there was no alternative was a good way of filling in the gaps in the Jolla store.
However, as I've got older I find large phones more and more unwieldy, and I couldn't find a small enough SailfishOS phone to switch to. I'm now running LineageOS on a Jelly Star. The form factor is perfect for me.
Would I return to SailfishOS? Absolutely. But there'd need to be a small phone in the line up for me to migrate to.