Both men are unsure of where they fit in to the new order. Thomas, 21, makes his debut against Italy on Tuesday while 19-year-old Murray travels to Dublin with the Scotland squad. They are at a crucial point in their careers: do they abandon their education and hope to hitch a lift on the professional bandwagon; or should they play safe and get qualified but risk losing out to more committed rivals prepared to give up everything else?
Thomas is, by popular consensus, one to watch. A stand-off who possesses a mighty boot and mesmeric running skills, he is, according to his coach at Bristol, Brian Hanlon, "self-confident, arrogant even, about what he can do on a rugby field".
But Welsh rugby is in a state of flux and a battering at the hands of an Italian side which beat the best of Scotland last week could prompt sweeping changes. For all his potential, Thomas still has everything to prove at the highest level.
He also has a degree to obtain, in leisure management from Filton College, Bristol. At least that was his intention. "I am seriously considering quitting my course," he said. "It demands 26 hours per week actually at the college, plus an additional 12.
"I just don't think I can do that and achieve everything I want to in rugby. I want to be the best and that means giving 100 per cent commitment. I would not forgive myself if I failed to make the grade because I only gave it 80 per cent."
Thomas deserves a degree of sympathy, but he is far from neglected. On Tuesday he will receive a match fee, the size of which is still being negotiated between the players and the Welsh Rugby Union, and he is also in the privileged position of being a member of a specially selected Welsh training group.
Elite Rugby Cymru 2000 is a WRU initiative designed to identify and develop players deemed to have "enough potential to grace any side in world rugby". Besides Thomas, other caps in the group include Spencer John, Gareth Thomas, Craig Quinnell and Justin Thomas. Each is assigned a "mentor" to monitor their progress at club level, look after their welfare, and attend to their every need. The man looking after Thomas is the former Wales and British Lions centre David Burcher.
Now a building society area manager, Burcher, 44, watches Thomas play three times a month for Bristol as well as attending the odd training session. He insists it is not an overbearing relationship. "I would not dream of stepping on any Bristol toes," he said. "My sole desire is for Arwel to maximise his potential."
As well as specialist coaching, Elite Rugby Cymru 2000 offers career advice and, because Thomas lives away from home, helps pay for his food bill. Through Bristol he has free membership of an exclusive fitness club, a sponsored car, a club contract pending for next season and free kit from Adidas - a by- product of his relationship with the kicking coach Dave Alred. While he may be some way short of becoming a millionaire, for now the consolations are none too scruffy.
Thomas, who rose to prominence with Neath, acknowledges that the arrival of professionalism has changed players' perspectives. "I don't think there is as much loyalty and passion in Welsh rugby as there once was because people are now thinking what is best for them," he said. "There is now an 'American dream' factor attached to the sport. If somebody has nothing but rugby talent there is, or soon will be, the potential for him to earn fame and fortune."
From what he says, it seems that Thomas is gripped by the prospect of fame far more than he is seduced by any forecast of fortune. He looks at the adulation surrounding Jonathan Davies on his return to Wales and likes what he sees.
For the time being, Scott Murray would certainly settle for the fortune. The Edinburgh Academicals' lock was the only member of the full Scotland side masquerading under the "A" tag last weekend in Italy who has not been offered a contract (worth up to pounds 25,000) by the Scottish Rugby Union.
"I hear and read so much about the money in rugby," he said. "But the fact is I am on income support and depending to an embarrassing extent on my family to help fund my rugby. I am considering a part-time job because I can't keep taking money off my folks. It's just not fair on them."
Bearing in mind his obsessive training regime, it would have to be a part-time job. He undergoes three separate sessions each day in an effort to increase his bulk from 15 and a half stones to 17 by the beginning of next season.
Like Thomas, Murray can find little time to study and like Thomas he appears to have a firm future; it is the present in which both young men need to tread warily.