is a "simplifield IR" likely to materialise sometime in the next four years or not?
This one is really impossible to have a stab at. Four years is an awfully long time.
EASA has only just taken over FCL legally; they will need a year or two to get sorted, they will then be frying the most important fish first (which is definitely not a more accessible private IR) and in the meantime there is the "LAPL" which had the IFR option voted off it recently but apparently the matter is being re-opened by EASA who are in principle supportive.
So it's all up in the air.
Why do you say "4 years"?