The 3rd name would need to be someone who is hardest to replace.
Gilchrist is better than the next group of keeper batsman (Pant, Ames, Sangakarra, Prior) by about 5-7 runs. You could point to batsman who can keep like Flower, AB Devilliers but their glovemanship isn't as good.
I'd argue that you might lose more missing out on Hadlee or Imran Khan because they are around the top 10 bowlers of all time who can also bat a lot better than other top 10 bowlers. I was going to make a thread discussing the value of bowlers who can bat but I need to comment on some threads first
I don't think a pure pace bowler is the 3rd name because they are well stocked & the difference between the very best isn't huge.
Spinners you've got Warne & Murali. You can make claims for others but those 2 seem to be of a higher regard.
Openers is interesting because you've got a lot of people who swear by Hobbs but Hutton & Gavaskar probably played against tougher bowlers & carried their team more. Sutcliffe is also up there with his average.
And there are a number of candidates amongst middle order batsman
So considering that Gilchrist has no equivalent peer I would go with him.