Removing Roth

Are they any foreseeable issues with removing a Roth elective deferral option from a 401k plan?  

No, Roth contributions are not a 411(d)(6) right, any more than regular deferrals are a protected right (we can always amend the plan to eliminate deferrals).

Of course, you have to make sure you keep all the language and admin associated with the existing accounts even if you eliminate new Roth deferrals (or non-Roth deferrals, for that matter).