maybe before that date... as a pve faction and after as a playable faction, with the latest fluff we can have multiple necron faction with no problem
At this point putting in pl Necrons is more about time and production constraints rather than difficulty of implementation. It's been stated that the next faction put in would take over a year at least a year after launch and even then Necrons would be competing against the much more popular Tau among others.
well I know that, but we should still consult it to know which factions we will beat out in a popularity contest!
IG is too tricky because the individual soldiers are so weak. Daemons are tricky because they cannot be customized. Dark Eldar are tricky because they would be very close to the Craftworld-Eldar. Tau are tricky 1. because their combat-suits are so ubiquitous, 2. because the combat-suits are so big that they make easy targets, 3. because they need the Kroot for close-combat. Necrons would be easier, because they are straight-forward.
this makes quite a bit of sense lore wise as well, as awoken tombs take time to fully power on, we could be fighting tyranids one minute, then BAM, canoptek scarabs and wraiths start crawling out of mount "Not an inactive monolith"
tau will be the easyest to implement, followed by the DE and necron the suits will be elite choice, so no worries about them becoming more powerfull than standard troop the kroots are not (and neither really been) melee troop, nowadays they are more like a IG with no armor and a bolter-like weapon, they used to have S4 and 2 attack, not anymore the tau are able to do damage in CC, but less than other armys