I suspect it is quite likely. EASA scrutiny of third country aircraft is an active proposal in the amendment to the regulation which set up EASA and this issue was flagged with ICAO in 2004. They have to step carefully so as not to undermine the convention, but an extra level of checking seems to be certain. Although an outright ban on non commercial foreign registered aircraft does not appear to be a firm proposal yet I suspect it is only a matter of time. Once EASA "certificates" third country" operators in the EU then every aircraft not certificated could be judged to be private and therefore required to be re-registered. What with the recent DoT consultation on this issue and a similar issue being raised by the Frence a while ago I think it would be foolish to ignore this as a very real possibility.