It will be mostly white men. Why? Trump prioritizes loyalty. They're mostly white men around him with some white women. Trump has the ability to be diverse like I have the ability to repress my snark.
Here's another thing to think about, some people on this forum ask why Trump should select a female or a minority if they aren't "as qualified as white dudes"? Well, if you have surrounded yourself with white people most all your life, you aren't as inclined to know what females and minorities out there have to offer. If Trump wants to drain the swamp and hire some new blood for his cabinet, who says he has to pick a female or minority from the political arena?
He wanted to hire Ben Carson, which actually is to his credit in this regard, but Carson declined.
Honestly, I don't think there's racial intent here. It's just he's always surrounded himself with largely white male executives and advisors and white people. This is who ends up in his Administration. Trump's connection with minorities are extremely lacking. Like, white crust Bush 41 level. W had interacted with Latinos as governor of Texas, Reagan was obviously in a diverse state as CA governor.
But Trump? Never had real minority outreach and neither does his team.
Compare to the last GOP presidency. Bush 43 made a concerted effort to recruit and diversify his Administration, including two black Secretary of States, a Latino Attorney General, and to replicate an Administration that looked like America. A lot of that stuff dates to Bush's governorship in Texas, where he was governor in a state that was very close to minority-majority and he was highly aware of the need to broaden and diversify the GOP coalition.
Now, compare to Trump's experience, which has been rooted and centered in lily white Manhattan, Queens, and New Jersey, and his social circles, which is heavily white.
This is the other reason why prior political/governing experience is needed to become president. You become aware of the country you're supposed to govern. You're aware of the people, the populations, everything. It's why most of our presidents have been governors and senators and military leaders.