Eng could pick this team and it would be 20 years old and under by the time the next world cup comes around:
1) Vunipola (24), Auterac (22),
2) George (24), Cowan - Dickie (22), Heywood (23)
3) Brookes (25), Thomas (23), Sinckler (23)
4) Itojie (20), Symons (26)
5) Launcbury (24), Kitchener (26)
6) Ewers (24), Clifford (22),
7) Kvesic (23)
8) Vunipola (22), Morgan (26)
9) Robson (23), Youngs (26), Cook (24)
10) Slade (22), Ford (22)
11) Nowell (23), May (25)
12) Eastmond (26), Hill (22)
13) JJ (24), Manu (24)
14) Lewington (24),
15) Watson (21), Daly (22)
Then you got the likes of
Waller (25), Balmain (23), Barrow (22), Stooke (23), Beaumont (22), Ludlam (19), Pearce (24), Harrison (25), F.Burns (25), B.Burns (21), Devoto (22), Atkinson (25), Walker (22), Earle (21), etc etc
What's great is that team could have been picked for the six nations and i wouldn't have been to upset (Its not our best ATM but it would still be pretty good) but with 4 years experiance under right management could be brilliant.
Obviously form will happen players will go up and down new players will arrive etc.