Paradox Interactive says on its forum that they are “happy to announce Cities: Skylines is coming to Xbox One!“ and that more info will be shared “soon”. They also claimed that the development of the Xbox version won’t hurt the PC-side.
“A small note that you should all know: This announcement doesn’t mean
that we will stop working hard on the PC version, not at all, it just
means that we are taking Cities: Skylines to a new level!”