Is there any way to predict libhybrisablity of those devices? (OnePlus 3, WileyFox devices)
There are no Sailfish/Ubuntu ports yet and the specsheets are really vague.

Can we assume that for smartphones A, B which have the same model of a subdevice X (e.g. cellphone antenna): if X works perfectly on A, then X works perfectly on B (under libhybris)

On the other hand, maybe it's not worth investing right now. Maybe some keyboard slider will appear in 2017? (BB plans to release one)
I'm in doubts.

And what do you think about Meizu MX4, Pro 5 or BQ Aquaris E5? These had a version with Ubuntu Touch, adaptation seems to be on GitHub.