Haswell Makem
Winger
These lads are decent prospects, but don't look anywhere near the first team at the moment IMO.Watson, Kelly and Harrison Jones.
To me the yardstick is standing out week in and week out in that environment and although the 3 you have mentioned have had some good games, they don't have the consistency that say Chris Rigg had. Out of the 3 mentioned, Watson looks the closest, but even his coach (Murtagh) said he is not ready. The one you did not mention is the goalkeeper Young, who looks the closest to me.
I would class some of out first team squad in that category mind (Hemir and Burstow spring to mind, who did not look anything at U21 level)