People need to realise de Gea might still peak in different areas of his development. His reflexes may have been God-like up to now, but these will slowly fade away and be replaced by other sides of his game, such as better positioning and doing better when commanding the area. A goalkeeper's career isn't as short as an outfield player's is and they have much mire time for improvement. Remember his early years? Who says there's no way he improves his weaknesses now as well?
I know I might be biased, but the guy broke his back to carry the sorry excuse of an outfield ten we had not ling ago, he deserves more than anyone else a chance to redeem himself. Putting Henderson before him just after a single good PL season is massive disrespect towards David.
Also, Romero always comes before Henderson as well, he's been the best second choice goalie a club could ever want, no way he doesn't get a full season shot in my books, if we ever have the stupidity to get rid of DDG.