When they say “only support”, it seems that they mean “will only test on.” Salesforce won’t limit the application from running on unsupported devices, and they will even accept crash reports from those devices. However, they won’t be proactive in finding bugs on those devices nor will your crash reports be prioritized. Which is likely no different than being unsupported for a lot of people, but I thought it helpful to be precise.
“will only test on.”
That, and they will only fix issues that are reproducible on supported devices. Key excerpt from Salesforce’s support doc:
Salesforce will continue to address issues that can also be reproduced on Salesforce1-supported devices.
Unmentioned in the article is Salesforce is also dropping support for iPhone 5 and 5C.
Does Salesforce really have enough sway to push people to buy those phones?
In enterprise environments where “vendor support” is important, very possibly. I doubt it’ll make a difference to phone purchase choices outside of that arena though.