Can see what you are saying but there are problems here, you say that the thing England have at the moment is very rare but is it really? Think you can argue that Australia have the same thing right now, they are ALL proven test performers apart from North who has done exactly the same thing as Trott, scored an excellent hundred on debut, (plus two a couple more) followed by some unconvincing performances."Lack of alternatives" is often a deliberately negative way of looking at "the best players are currently in there". Apart from the fact that the latter is just about all any cricket supporter has any remote right to ask of selectors, the instance where you can look at the seven best players to bat in the top seven and say that, in a Test starting tomorrow, you could have reasonable confidence in them all is very rare - for England or anyone else. Even West Indies between 1976 and 1986 and Australia between 1989 and 2006/07 (two of the best sides the game has seen, which current-England are not remotely close to being) had such a thing only for a season at a time, absolute maximum.
And BTW, currently England have in the way of batting alternatives Carberry, Shah and Joyce (and, maybe, whisper it, Morgan). None of whom are write-offs with no realistic chance of Test success - if any was brought in in place of one of the top seven tomorrow I would believe it possible that they could succeed. You can never, ever know with an untried player, but all of them have something going for them.
As for those England alternatives well obviously there might be some potential players yet to surface but what I meant was that unlike in the past with England there is not a player with previous test experience that is really pushing for a place.