I wouldn't read too much into the Ardboyz going "No Longer Available Online".
Prior to the pandemic it was a pretty good indication for which kits get redone but since then it has happened more and more often that stuff just goes no longer available for a while and is back afterwards. For example right now the EU store shows the Alarith Stonemage, Sigvald, Skarbrand and the Mortisan Boneshaper as no longer available and none of them have a chance of being replaced.
And the Ironjawz SC going no longer available is also not really important since it is still a Start Collecting which are being replaced by the Vanguard sets. The only reason that hasn't happened for them and Stormcast yet is because they where the starter Battletomes (since Ironjawz is part of Orruk Warclans). For 40k it also took longer for SM and Necrons (9th edition starters) to get their Combat Patrols.
Though it did take a bit longer than I expected and Khorne also still has the SC available but that is probably because of the models locked to that box. They could put those sprues up as direct only on their own like they did with the Dominion sprues but since that wouldn't be a big change to how they are sold now I don't think it would even be worth the work to change that so the Goreblade Warband will probably stay as it is. Maybe get rebranded as something else than SC.