OK. So have I got this right? Gotama Buddha (and all the arahants) are still around in a mundane sense - i.e. they (mundanely) get reborn and that just carries on forever (I might cheekily say “for eternity” 
), but they are now not suffering anymore - saṁsāra, but not as we know it, because contact is not ‘ignorant sense contact’ anymore? So when an arahant says, this is my last birth they are talking in a supermundane way? Or is there some connection that isn’t stated?
Edit: Actually. I think I need to read that pdf that you posted to see if my questions are answered there.
Edit2: Just dropping this link in here as I think it’s relevant.