[averros]

The future missiles are going to be shiny.

As in "mirrors".

The BIG SECRET of directed energy weaponry is that there's a very simple and cheap method of reducing absorbed energy by orders of magnitude - reflect it in arbitrarty directions (or even towards the source if one wants to be naughty).

The sensors (which have to absorb EM radiation to function) are vulnerable, but can be easily protected by shutters for the duration of attack. Modern inertial navigation units are well capable of providing precise guidance without any external data.

[waste_monk]

This already exists somewhat (e.g. antiflash white paint on aircraft expecting to operate in a nuclear conflict area) but given that today's environment seems to favour stealth (you can't lase something you haven't detected yet, and considering how fast these missiles move the trade-off in survivability vs. detection time and thus time for the target to acquire, track, and shoot down the hypersonic missile is probably not worth it) I doubt mirrored missiles will come into fashion.

But, I am very much an "airchair" weapons technologist so I'd be interested in seeing arguments for the contrary!

[StrangeDoctor]

Just have a wide range of frequencies you can use, every material absorbs some part of the EM spectrum

[A2017U1]

An ablative covering negates this.

Hope they have enough time to aim in the same spot.