A great achievement for Mike Dean! Up there with the very best referees in the PL era.
Martin Atkinson has done 397 PL games I believe and Andre Marriner 323. I'm not sure if they'll quite get there - Atkinson would probably need to do at least three more full seasons and even more for Marriner.
Michael Oliver is on 250 after almost 10 years - he's young enough to get there if he continues refereeing in the PL until a reasonable age and doesn't move on early like Clattenburg/Webb/Poll.
Agreed. List in DT (excluding this weekend):
Dean 499,
Atkinson 397
Poll 329
Marriner 323
Dowd 308
Webb 298
Clattenburg 292
Riley 283
Halsey 279
Wiley 274
So Atko could be there in 3-4 seasons but will he go on that long? And, as you say, Oliver could be there in say 10 seasons, assuming he doesn't drop out early as for example Clatts did. A milestone indeed for Mike Dean.
Looking further back (BAFRA #217), I suspect Jack Taylor must be near the top in terms of games refereed on the FL, particularly as he was very much in demand throughout his time on the list. Wiki refers to him taking charge of over 1000 games, although this would have included internationals and European games as well as FA Cup and League Cup games. Paul Danson was another who was on the FL for 19 seasons as was (I believe) Andy D'Urso.
Edit - great tribute to Mike Dean in today's Daily Telegraph from none other than Keith Hackett, his first boss on the PL. Under the heading. 'arrogant tag unfair on dedicated Dean', Keith talks of a 'superb referee who is a credit to his profession ahead of his 500th match in the PL'. Mike was apparently an early member of the 'red wine' group on the PL, with Poll, Barber and Dunn, although Keith is quick to point out that their penchant for a spot of ruby did not detract from fine performances consistently from all four of them!