but to sit at my right or left is not for me to grant. These places belong to those for whom they have been prepared.
What is interesting here, is that Jesus does not deny the existence of these 'positions', nor that they will be granted for two specific individuals. This is of profound significance.
While one clearly sees that Jesus completely up-ends the disciples expectations by saying that the greatest is the servant, and that many who are first will be last, He in no way denies that there is position within God's Kingdom.
Speaking of the Law, He said,
Therefore anyone who sets aside one of the least of these commands and
teaches others accordingly will be called least in the kingdom of
heaven, but whoever practices and teaches these commands will be
called great in the kingdom of heaven.
There is a greater and lesser in the Kingdom, but Christ's point is that it is through love, faithfulness, and service, rather that something else (say, performance).
Whoever humbles himself like this child is the greatest in the kingdom
Again, Jesus describes those who are greatest as those who are humble like children, and who live and teach His commands. All throughout His teaching, He describes what it is to be like Himself, who is Himself the perfect portrait of greatness.
But, as for the specific two individuals, well, of course the Word doesn't say. Any speculation as to actual identities must, it seems, take into account AT LEAST 2,000 years of human history, considering every individual who either outwardly or inwardly confessed Christ. We are talking about probably over 10 billion people (random guess).
But, we have to remember that God's accounting looks different than ours. As Luke 21:3 says, the widow put in more than others, because she gave all out of her poverty, and the others gave out of abundance.
- God has prepared these two positions for specific persons.
- We have no way to know (in ourselves), who they are.