Messy - Need to unroot...international move topic

Folks my apologies for the general post but I have a number of variables and not sure which are relevant.

I have a rooted, custom rom AT&T with the following:
I have a PN0712000
S-OFF
CID 11111111
Unlocked

I have moved to Amsterdam and need to get back to stock to run MobileIron (kills me but needed). I can blow up the phone and rebuild to stock...but now I am unsure.

New Sim is from KPN....

If I go back to stock and then depend on OTA for updates...how would that work? I cant have root on this device.

Any advice?