But Boyd was quick to praise the 'outstanding job' Hinkley has already done during his trial spell with the black, green and gold.
The 23-year-old featured for the first time for Saints in the Mobbs Memorial match on April 12.
And with injuries in the first-team back row, he was then given a place on the bench for the crucial clash with Harlequins little more than two weeks later.
Hinkley was only supposed to be given a cameo, but with Juarno Augustus forced off due to injury inside the opening 10 minutes, the former Gloucester and Exeter forward stepped up.
Hinkley was a contender for the man of the match award as he turned in an incredible debut display to help his side secure a vital 32-31 win at cinch Stadium at Franklin's Gardens.
And speaking at this week's media day ahead of the Gallagher Premiership trip to Saracens on Saturday, Boyd said: "He's done a very good job for us.
"I thought he played particularly well against Harlequins.
"We weren't sure whether he was ready to be dropped into that Quins game. He was getting close but he'd trained particularly well during that week and we thought if we could get 60, 70 minutes out of the other guys and give him a little cameo at the end, it might give us an idea of what he can give us.
"As it turned out, he ended up playing about 70 minutes and he did an outstanding job so he's on the path."
So will Saints be holding on to Hinkley beyond the current season?
"I'm the wrong person to ask there," said Boyd, who is leaving his role as Saints director of rugby this summer as he heads home to New Zealand to move into a consultancy position with the club.
"Paul Shields still continues to lead that recruitment and retention part, and it's being directed now by Phil Dowson because it's going to impact him going forward.
"So you need to speak to Phil about that."