I think that Necrons can still match up well versus eldar/tau, however I think its going to require different tactics in order to overcome them both. I'm beginning to think that wraithwing and scythewing are not the sure fire way to win anymore due to a few problems that necrons innately have. For one, our codex struggles to deal with 2+ armor
MCs at range (such as the riptide) as well as the high toughness targets (T 8 or higher like the wraithknight). We generally deal with them with warscythe, wraiths, and
MSS, but all of these require us to get into melee combat. With the amount of small arms fire coming out between the before mentioned codicies it hits this delivery system extremely hard. What's the difference between 6 wraiths and 12 marines against
str 5+? Nothing. They both go down the same way. That's not saying wraiths are useless (they are still amazing), but it's much harder to rely on them to be an end all be all unit like we are used to using them as.
Unfortunately at range its also difficult for us to deal with these things as well. Its extremely difficult for us to get any heavy hitting low
AP firepower without paying a lot for it and difficult to get it in volume (Yes, tesla destructors are our best friends but against riptides the
Ap- really hurts here). Our most cost efficent way is through Crypteks of Destruction, but 5 will cost you 175 points-175 points for a fairly fragile unit (unless you keep them in a ghost ark) or you need 5 troops to find a place for all those lances, but this means that you're going to have a weak distribution of fire as well as a lot of potentially wasted fire from the troops they are attached to.
Another way is through heavy destroyers. These platforms are fast, accurate, but also fragile and expensive. 180 for just 3. Yes they are T 5 and have a 3+ in a world of Heldrakes and any concentration of fire power really hurts them due to small unit size and high cost. You need to have other elements on the ground to shake focus from them and let them do their work. That said due to preferred enemy they are one of the best
MC hunters in the game due to always rerolling that 1 to wound.
However, as a counter point we do have advantages versus both these lists. Mobility for one. We have one of the best (if not the best) transport in the game. Due to rules the nightscythe not only protects our troops but comes with high fire power and extreme speed as we all know. They are also decepively tough due to the hard to hit rule (though I understand the mitigation due to all the skyfire coming out lately).
Secondly, and most importantly we have durability. Both Eldar and Tau struggle against
AV 13 and higher, and no one can spam
AV 13 nearly as well as us. Meaning Ghost Arks, Anni Barges,
CCBs, and to some extent Stalkers. Ghost Arks provide our squishier Warriors with a hard exoskeleton as well as a gun platform where a full unit of 10 and the side guns can let loose 30 shots at rapid fire range. Annihilation Barges, well there's not much to say. We all know their amazingness.
CCBs are still a good way to provide a distraction and an alternative delivery system for Warscythe wielding Lords to cut down and bully (for that's how it should be treated) lesser units. Ironically it's also a decent
MC hunter due to
MSS still working despite the Lord not being able to be locked in combat. Stalkers although expensive are able to be force multipliers, giving troops like Tesla Immortals deceiptively strong fire power. All of this leads me to my next point: Hybridization.
Now, what I think needs to change is going from wraithwing/scythewing to a hybrid list. One that combines all of these elements to create a balanced list that stretches fire power. 5
AV 13 vehicles and 2 Scythes gives you durable transports as well as strong supporting fire for your wraiths/
CCBs whose roles are to provide counter-assault or act as distractionary targets to take pressure off things such as your heavy destroyers. This allows your squisher but heavy hitters to deliver strong consistent fire power on high priority targets (like Riptides/Wraithknights) or provide a way to consistenly put glances on things like wave serpents. By hybridizing we change the dynamic of how our army works and how people will deal with us. If they're prepared to deal with fliers and massed wraiths and come against more than the usual 3
AV 13 vehicles, the standard way they deal with these threats are now stretched to their limits. At least, this is how I hope it plays out.
Mind you this is purely opinion, feel free to disagree and make your own points!