Definitely there should be a plan for continuity, although not necessarily continuity of the same methodology.
Although he probably will be there next year, nothing I have read in the media absolutely confirms it - there is still talk of him needing to discuss things with the DCC (so the same scenario as we had with Daly at this time of year).
I suspect he will stay, we will have an ok year as there is a decent enough team there (but we will be well short of the top 3), and then someone else will takeover and probably bring things on as I suspect there will be low hanging fruit that can fixed after Cunningham leaves. Cunningham will get the credit then for bringing on the new lads with little mention of the years in between.
But from the quotes I have seen he is setting a target of making a semi final next year. Lets see how it goes…