Dark Reapers used to be a much more flexible unit back in 2nd edition, and this rumor pushes them in that direction with the addition of Eldar Missile Launchers. The rumor actually states that they will get these missiles instead of, but personally the rumor below is highly suspect  because of its source.

What I really might expect out of Dark Reapers is not necessarily due to this rumor, but that Games Workshop has repeatedly looked backwards for options and new ideas, and included them into current codices. With that in mind, Eldar missile launchers and Dark Reaper Launchers might both be on the table for the new codex.

The rumor here is higly suspect, because of its source. I have put it up today because it does make sense following GW's trends lately. Please take with salt

via Drakeus
There is a rumour in the air that Dark Reapers are going to have EML's instead of Dark Reaper Launchers (heard in GW Hobbystore from the manager). If that is true, we will have a decent boost for them!

via Hellebore (not a rumor, but comments on Reapers in 2nd edition)
Missile launchers are what Dark Reapers USED to carry in 2nd ed. They were using full on missile launchers that could fire pretty much any type of missile you wanted if you upgraded them - they were 67 pts each with frag/krak and could pay 5pts per additional missile type - melta, plasma and anti plant.

So for 82 points (a tactical marine was 30) you could have a T3 3+ sv model with every missile under the sun. Squad size was 3-7.

Currently you can only get up to FIVE reapers in a unit so i really fail to see how giving them back their missile launchers would be a bad thing. That's not much different to having a devastator squad with 4 missile launchers, and more fragile at T3.

What it will do is turn dark reapers into what they were, long range vehicle destroyers that could also destroy some heavy infantry and light infantry. If you gave them EML then that would really halve their MEQ killing power, plasma missiles won't really cut it and they only fire 1 krak each.

Doesn't seem that bad to me. I would really hate it if they invented a whole new aspect just to the fill the role dark reapers originally filled in the first place. Just seems totally unnecessary. It would be like giving assault marines bolters and then making a new marine squad called an 'attack squad' that had chainsword and bolt pistol. Pointless.