Likely to be massive consternation among horse racing fans in Ireland if RTE (who have dropped nearly all GB racing coverage bar Aintree and Cheltenham in the past decade or so) don't pick up the slack. (Or unless these rights include Ireland).
That could be interesting as this is something which would work well on UTV Ireland I'd have thought.
At the moment UTV Ireland have repeats of Emmerdale or Coronation Street on weekend afternoons so from 2017 if UTV Ireland are allowed to show the rights every saturday that would probably be on ITV4 and wouldn't be shown on RTE it could as you say do well. It would also do excellent for them if with ITV backing they could take the rights to big meetings like the Grand National from RTE.