I think you misunderstand how Windows is going to work going forward.
Microsoft has shifted to a different development model, one peppered with more features over time rather than large XP > Vista-like upgrades every so often.
1. W10M's development will never be "finished," they will continue developing new updates in the near future.
2. The current stable branch, Threshold 2/10586.xxx is "finalized" and is only getting bugfixes now while MS works on the next upgrade. And as long as there's another piece of software under development going forward, there will be Windows Insider. Insider is sticking around.
So basically, your 925 has been thrown under the bus. Your only hope is to get on the Insider program and get a soon-to-be-outdated Windows 10 Mobile build or buy a new Lumia, which is what they want instead.