in general, i think if hedge funds & other major liquidity providers want to trade or hedge with fx futures they will just do it. with or without reuters. the reuters terminal will just make it easier - not present a reason or a new business case to trade a new product.
if anything volumes have dropped during may for the us main hours (7.20 ~ 11 am cst)
this week i have noticed volumes increase however for the london/euro hours slightly - but this could well be down to activity from the referendums?
this is just technical though - big move in the morning, tight dry trading range/consolidation afterwards. happens in all markets as we know.
cme have also been putting on their horse & pony show (global fx summits) around the world as well to increase volumes.
so overall id say there has been little impact. i dont expect there to be either.