Imagine the Bard, Sorcerer, Warlock, and Wizard were not in the PH1. Someone says "the Eldritch Knight gets you pretty close, a few tweaks and you're there." That's what this thread sounds like to me.
IMO, 4E (which I liked!) had much more than 5E does of powers or abilities that bend reality without being magical. Things like the fighter's "Come and Get it" were the most infamous, but a lot of the warlord's powers were along those lines as well. Many of them were also directly related to the kinds of tactical details that 5E did away with in order to speed up combat. So I think a lot of the 4E warlord mechanics are rather antithetical to 5E design.
So there are a few options:
1) Come up with a 5E class that feels mechanically similar to a 4E warlord. For the reasons I stated above, I think that's unlikely to work well.
2) Find a way to play a character in 5E that fills the thematic role of a 4E warlord (and feels like a warlord), even if it doesn't have many unique mechanics.
3) Come up with an entirely new, unique set of mechanics that fits the warlord and also works well with 5E.
I've been mainly thinking about 2, but 3 would be an interesting project.