The IMC Rating is a UK national qualification that has nothing whatever to do with EASA. As a national qualification, it could not be entered into a Part-FCL licence and so, in 2013, the UK CAA unilaterally began entering it as an Instrument Rating (Restricted). EASA then retrospectively permitted national qualifications to be entered in Part-FCL licences, subject to certain restrictions, by amending Article 4 of the Aircrew Regulation but this is only effective until 8 April 2019. Meanwhile, EASA has been working to develop the 'Basic Instrument Rating', an EU version of the IMC Rating, the Opinion for which has recently been passed to the European Commission.
Clearly, there is little or no chance of the BIR coming into effect before 8 April and so there are a number of options:
1. The effective period of the Article 4 amendment is extended - unlikely as this is primary legislation, but not impossible;
2. The UK CAA continues to enter the IMC Rating in Part-FCL licences regardless;
3. The Article 4 amendment expires and the IR(R) is no longer entered into Part-FCL licences.
In the latter case, the IMC Rating may continue to be included in a UK PPL, which may be held alongside a Part-FCL licence. Whatever happens, there is no suggestion that the IMC Rating will not survive as a UK national qualification, at least until the BIR is established.
To be clear: The IR(R) does not exist, it is nothing more than an administrative fudge engineered by the UK CAA. The qualification that people hold is an IMC Rating, a national qualification detailed in Schedule 8 of the UK ANO