By The Gig plan

I currently have a by the gig plan and share data over 3 phones.   This is perfect for me because we use very little data.  I know Xfinity is phasing out "By the Gig" and if you change your plan, you cannot go back to By the Gig.  My question is this.  If I add the Mexico and Canada plan for a month and then cancel it, will I be forced to change to Unlimited data for each phone or can I keep my current plan?