It shouldn’t, since your incoming routes are set in the Incoming Destination.
It depends on how you implement your Zulu calling. If you use Zulu as a secondary destination (like on Find Me/Follow Me) then you should be good to go. So, for example, if you use FMFM to send desk calls to people’s cell phones after the desk phone times out, then you don’t have to do anything. If, on the other hand, you want them both to ring, then yeah.
I don’t know how you’re planning on using Zulu, but if the model you choose is “as an alternative” to the desk phone, you probably want to avoid having your Zulu phones tied into the ring groups. In fact, I can think of several reasons why this would cause consternation within your user community (both phones on my desk are ringing, etc.) If, on the other hand, you are using Zulu as the only phone for some people, you will need to strategically add the phones that you want to include.