I hope that you reconsider the drop rate of ethereal items. If they are to be half way between legendaries and primals. Then you might have the problem where the majority of the players will see this season as an extension of season 23.
You past seasons that had a real impact on players were felt from day one. Why should ethereals be different. I understand what you are thinking. We put these awesome items for players to chase after. Thinking that players will sink more time into season 24 than any other season chasing after them.
But the problem is that players might not have as much fun with them if they are only able to use them for a few weeks due to getting lucky enough to find one near the end of the season.
They are not gonna be around after season 24 ends. So why not make them impactful from day one like you have other seasons.
I would suggest you make their drop rates where they are around 1 out of 15-20. This way somewhere around 1 out of every 15-20 legendaries an ethereal drops. Players will have a much higher chance of finding what they want. Also you might reconsider and let players gamble for them as well as making a cube recipe for them as well.
Using the DH as an example. Upgrade a rare crossbow will give you the ethereal version. The same is true for the one handed DH crossbow and the two handed bow. Keeping the cost for the upgrading low similar to how it is for legendary items.
There have been good seasons that were so good you extended them. Players played more in those seasons because the season buff was felt the whole time. Instead of being felt for only a little while.
I hope that you will reconsider ethereal drop rates and maybe add in the other ways as well. My real fear is that this season could be a meh season where you would have to jack up the drop rates of them to insane numbers during the season just to handle the complaints of not seeing enough to find what they are wanting to find.