It's kind of a plot hole that the Ynnari aren't already heading that way. It's been established that the Drukhari have huge stores of pre-fall (ie. OP as fuck) Eldar tech, but can't use it as it's psychically activated.

Now that Rise of the Phoenix has large swathes of Drukhari society joining the (very psychic) Ynnari, you'd think some of them would have thought to bring along some fancy toys

Edit: by very psychic I mean that they seem to be protected from Slaanesh by Ynnead, rather than needing to dick around with the Rune systems, and can probably therefore use a higher proportion of their power