That all depends on how much or how little punch you like your Englishes to have. The general consensus on here (personally, I haven't been cellaring long enough to opine on this, one way or the other) seems to be that latakia loses some of its oomph after a few years, so at roughly the decade mark, it's safe to say you can expect some of that. Some would consider that a problem, others would welcome it, particularly anyone who has experienced latakia burnout and has come out the other side of it intact. Of course, there's no way to gauge precisely how much it has dissipated without cracking and sampling one, and even that's just a window into one particular tin--one of those May '12 tins could be completely different than the other one with the same date! Sure there are general patterns to be found, but overall, tobaccos are very fickle.
On the plus side, if you crack a tin and are disappointed with the results, you've still got two sealed tins (read: a bevy of competitive bidders on Pipestud or Tinbids). Then you can finally snag that Darnell Nurse bobblehead you've been eyeing for the longest time...