After watching the podcast, the dev team made it clear that hybrids will do respectable damage but less than pure damage dealing classes. Perfect, makes sense as hybrids have more utility tools traditionally like Innervate, windfury totem, etc.
There is currently a thread that has gained major traction on the wow forever beta forums covering Spriest issues and I wanted to bring light to it on reddit too: https://us.forums.blizzard.com/en/wow/t/a-petition-to-blizzard-about-shadow-priest-design/2367686
As it stands, shadow priests will not be desired ever unless they bring top tier singletarget damage to the raid. Which they wont as stated in the dev podcast as they desire for all non-hybrid, pure dps classes to fill that role. Shadow Priest were a meme in classic, a true utility hybrid in tbc, and finally a true caster dps with utility and AoE in wrath. Many spriests were hoping Forever would do something unique with the spec, make it a utility like in tbc, or have it be a genuinely viable dps like in wrath and the popular opinion is that none of these have occured in the forever shadow priest design.
Core Issues:
They are competing for a spot against healing priests to provide priest buffs which is a battle for a raid spot shadow priest will not win.
ONLY caster with all valuable utility gone that was available in tbc and wrath. Our only utility left is party wide vampiric embrace which is the weakest version of it across era, SoD, tbc, and wotlk and also very often overlooked and not valued in a raid comp and deservedly so.
ONLY caster dps with no AoE as multidotting is tradionally weak dps and hurt even more by ramp up time.
Now, looking at other hybrid caster specs for comparison.
Balance Druid:
They have 3% crit to party, spammable AoE hurricane(cd was removed) that also reduces ALL mobs attack speeds by 20%, supercharged thorns via moonkin spellpower for tank, 2% chance for boss to miss attacks, an extra battle res, and an extra innervate. And now lets look at spriest, the worst version of vampiric embrace healing in recent memory ... and thats it.
Ele Shaman:
All totems support including windfury. 6 second cd fire nova AoE, magma totem aoe, and chain lightning for incredible cleave.
Possible Solutions
Return a valuable utility to the spec. The popular opinions are a mana battery function or a 5% spell damage increase to boss. Both are utilities that have been iconic to shadow priest in classic expansions
If Multidotting is the ideal shadow priest AoE playstyle, then support this playstyle. Add in talents for SPriest like resto druid got that reduce gcd time for the druids HoTs. This allows quicker spreading of DoTs to help ramp up issues. Shared Pain is another solution as this allows spreading multiple SWP's on the same global. A third option is the implementation of the iconic spell mindsear.
Remove the high threat modifier of mindblast as this is something tbc and onwards removed and it was the correct decision.
Fix talents. Improved fade is a talent that is never taken in any build and it has been this way since 2005. Also shadowweaving now only effects spriest currently in Forever so then make it be a buff to the spriest instead of debuff to target to help ramp up times. This was done in wrath and was a great change.
With these changes, Shadow priest could maintain its hybrid spec status while also being desirable to dungeons and raid environments.