Gameplay was already fantastic with the Treehouse footage in June. Not really concerned. Looks great. Plays great. Will be great.
There are many games out there that look great and end up playing like poop. Doesn't seem to be the issue here.
I'll be honest I didnt gel with Samus Returns, I played for 45 mins and I just wasn't sucked in like I usually am with Metroids (Super actually took the longest to hook me, I played Zero Mission, AM2R then Super [and after Fusion]) and I put it down, but I sense a Switch re-release in the future so I'll give it another go then.
Having said that I think all my complaints about SR are shown to be fixed in the treehouse footage of Dread as you say. The counter system looks way more fluid in this one and you dont need to stop to do it, as far as I can see. That seems like a brilliant addition to the Metroid power journey, where you start out fighting enemies from a distance or even running from them to avoid potential health loss from your very small starting pool of health, then you get the tools to kill them more easily, then without hardly any challenge, then you can later obliterate them easily and finally you get abilities to just bypass them or blast through them at high speed like (a) super(wo)man.
This adds another layer where you can take them out quickly right near the start (I presume you get the counter early) but its a timing-based skill check and not as easy as stopping and picking them off from a distance so you have a choice. Even if you aren't the best at timing stuff you can still learn my muscle memory as you go.
So it rewards high-skill players straight away but doesn't leave casual players in the dust either, they can learn over time. I think its great if it works like how it appears in the playthroughs seen so far.