Since humans trust their Mk1 eyeball far beyond any other sensor, and all those fancy sensors can fail. When they do fail, the Mk1 eyeball will likely still work. So I will expect troops into the far future to still use some variety of camo.
What colors are used in this camo obviously depends on what the local soils and vegetation look like.
If you've been assigned to a mission on Mars, then you'd probably want cadmium red and red iron oxide as your primary colors.
If you're feeling particularly evil, you could deliberately choose un-natural colors to force the brain to process the image. There's an 'amusing' little scene in Michael Z. Williamson's "When Diplomacy Fails…" where the UN Army's camo development team came up with a pattern that created another 0.4 seconds delay prior to shooting. Unfortunately, the colors used were fluorescent orange and pink with blue-purple highlights. (scene is on pp.65-66 in the paperback edition) Personally, I'm tempted to get a couple PanO minis to abuse with that paint scheme, because I'd never succeed in painting more than 2 minis in it! And I hate PanO.
Or you could assume 'chameleon cloth' that either passively or actively changes colors. Passive color-change is done by using itty-bitty dots of pure colors. To represent that on a mini, I'd just paint it a simple shade of khaki, call it done.
Active color change, you're talking about Predator stealth or the Therm-optic camo from Ghost in the Shell. For those, I like painting the model to look like it's base with patches of neutral gray, and the lines between the trompe l'oeil effects and the gray in electric blue. Or you could make clear-resin versions, but that's a lot of work.