TD, the decision to consider an earlier replacement of the R1 than was first envisaged has NOTHING to do with what is currently happening with the MR2!!
Think more along the lines of future support for only 3 aircraft once the MR2 is out of service... Do you honestly think that factories will stay open to provide parts for an aircraft type that is so old and of such few numbers? Do you think Rolls-Royce will keep a build-line operating to provide engines in such few quantities as would be required, when that engine type is otherwise extinct? (and yes, it's different to the MR2's engines).
Think "Rivet Joint".