The Scarlets have been warned that Ben Morgan will be "under pressure" to move to the English Premiership now has committed his Test future to England.
The Bristol-born number eight chose England despite being poised to qualify for Wales on residency grounds.
And former Scarlets back-row Dafydd Jones thinks the 22-year-old could now leave the Welsh region when his contract expires in 18 months' time.
"It's a massive blow for the Scarlets," said former Wales international Jones.
"I know Ben well and it was a pretty tough decision.
"He will be a loss because he will be under pressure now, I would expect, to go back over the Severn Bridge but we are grateful to what he has given us over the last couple of years, he has been playing so well.
"I don't know another Englishman playing in Wales so he'll be the first.
"He is a great individual and I think he has got another couple of hard decisions to make as he won't be short of offers."
Morgan started his career at Dursley in Gloucestershire before moving across the border to play for Merthyr Tydfil in the 2008-09 season.
The 6ft 3in powerhouse also played for Cardiff Blues Under-20s during that season before signing for the Scarlets at the end of that season. His contract at Parc y Scarlets runs until the summer of 2013.
England forwards coach Graham Rowntree has revealed he will be "looking to get him involved very quickly" as England prepare for the Six Nations opener in Scotland on 4 February.
But Scarlets coach Nigel Davies hopes Morgan still has a club future in west Wales despite pledging his international future with England.
Asked if it would be harder to retain Morgan when his Scarlets deal expires, coach Davies admitted: "I don't know.
"It is always harder when a player has made a name for himself and Ben has certainly done that and now he is to become an international rugby player."
And asked if Morgan would be under pressure to move to an English club, Davies replied: "It is something we have not spoken about.
"They have obviously been happy with the way he has been playing here and our style of rugby.
"He is playing regularly against a lot of the players that they play against in the Six Nations in Scotland, Ireland and Italy.
"And he knows the Welsh boys so I would imagine it is quite beneficial for them to have players playing outside their domestic league, particularly if they are familiar with the players they are going to play against for England."
Morgan had previously turned down the opportunity to play for England Saxons in the Churchill Cup, which would have ruled out any chance of playing for Wales after completing three years' residency.
But now the back-rower has committed to England and Jones, the former Scarlets and Wales flanker, believes the English have secured a "priceless" player.
"He has been a massive plus for us since starting his career here," said Jones.
"He is a great ball-carrier, he gives momentum going forward which is priceless in any team and there is so much to his game."