Neither Byrne nor Foley could be described as up & coming.
I reckon Byrne should keep his place as he offers something different to the other 4 (Robbie, Doyle, Morrisson & Elliott) whereas Foley is more like what we have already but not as good. I expect a fully fit Alan Lee or Daryl Murphy, if he can establish himself under Quinn (no better man to learn from), to put pressure on Byrne's spot. But I think Byrne has the spot for now until another player makes a compelling case to be in ahead of him.
In fairness to Foley, he actually did very well in his Irish outings but we're going back over 5 yrs now I think. Estonia at home was the last one I remember anyway.