Purdy will of course get another opportunity or two (or six like some of the names below), he's got some name recognition now.....but I don't think he'll ever come close to this year again. For one thing he has a long hard road just to be able to throw a ball at a pro level. For another he really wasn't that good to begin with. I'd say the same thing about Skylar Thompson, although he's already at a lower level at this point. Purdy has the name recognition that would get him in the door of the broadcasting industry, which frankly is as starving for talent as the NFL.
The recent history of 7th round QBs is not pretty, although it is interesting. Most are still trying to stick somewhere, some have even done big things in other leagues. Just going back to the Mahomes draft, you might recognize a few names:
7th round QBs
2022 (1 1st round QB, 9 taken overall)
Chris Oladakun - Cut by Pitt, on KC practice squad
Skylar Thompson - Miami, 3rd string, elevated to starter thru injuries, won week 18 to get into playoffs, lost playoff game but was competitive
Brock Purdy - SF, 3rd string, elevated to starter thru injuries, won division and 2 playoff games
2021 (5 1st round, 10 overall)
none taken in 7th round
2020 (4 1st round, 13 overall)
Cole McDonald - cut by Tenn, Ariz, TORONTO, now assigned to XFL
Ben DiNucci - Cowboys tried him 1 time, disaster, assigned to XFL
Tommy Stevens - Saints tried him at TE, cut him, Car and Giants also cut him. Played in CFL as 3rd string QB last year.
Nate Stanley - Went from Minnesota's practice squad, to IR, to cut
2019 (3 1st round, 11 overall)
none taken in 7th round
2018 (5 in 1st round, 13 overall)
Danny Etling - Patriots practice squad (but got a ring!), then they tried him at WR and cut him, Back to QB, cut by Atlanta, Seattle, Minnesota, BRITISH COLUMBIA, Seattle again, Denver, Green Bay, Jax, then Green Bay put him on practice squad.
Alex McGough - Practice squad for Seattle, then cut by them and Jax, Houston, Seattle again, then played in USFL championship game, winning as an in-game substitute. Look for him in April.
Logan Woodside - Drafted then cut by Bengals, cut by Tenn, played in the AAF and won offensive player of the week, then back on Tenn practice squad, picked up by Atlanta late last year.
2017 (3 in 1st round, 10 overall)
Chad Kelly (another Mr. Irrelevant) - Denver drafted, went on IR, was backup in 2018 until an arrest got him cut. Indy then cut him following a 2 game suspension for violating NFL personal conduct policy. Indy signed him again the following year and cut him. Two years later he was a backup in TORONTO and entered the GREY CUP in the 4th quarter with the Argo down 23-17 and led them on a Cup winning TD drive.