I think that a majority of people would accept that robots and-or AGI's are life forms when they can successfully reproduce, on their own in remote areas. May of course require a functioning local economy, with many different robots, some mining, some refining, some building, some designing, some researching. But all in all it is a viable proposition given enough time and resources.
I hope we'll achieve it within the next 150 years,
By providing alternative bodies for experiencing this cosmos. Particularly in eco-regions which are not inhabitable by traditional liquid-water based life forms. Such as Tanezrouft, and the McMurdo Dry Valleys -- which would be good hoping points to the inner and outer planets respectively.
Being only human I'm biased to believe things can be achieved in my lifetime, so I hope decades. But it may stretch until 2150 for all I know.
Of course how long and will it are two different things. There is a major political and even religious component to the success of having liberated robot host bodies available for incarnation.
People being unaware or unwilling to accept that machine intelligence with similar or greater complexity as homo-sapien brains has equivalent or greater amounts of consciousness, and thus equally deserving of the same entitlements as humans, could lead to major conflict.
Educating people about the realities and legitimate sentience of machine minds will be important to avoid conflict in the future.