Sadly, I don't think there is any risk for them for "losing developers en-masse to competitors".
Everyone who seriously considers to leave the platform has already left when they were acquired by MS and/or continued to work with ICE, and both of those only caused a miniscule amount of people to leave.
Everyone who seriously considers to leave the platform has already left when they were acquired by MS and/or continued to work with ICE, and both of those only caused a miniscule amount of people to leave.