Stall is dependent on AoA and AoA alone. Speed does not matter. If you reduce speed and maintain AoA your lift will decrease and you’ll no longer be in 1g flight.
I do think there is a bit of talking past each other. Yes, speed has a 2nd order impact on stall (reducing speed reduces the local Reynolds number which shifts stall location a tiny bit).
I think the concern was a sudden loss of lift ehich, since more change AoA is required to acheive the desired lift, one is more likely to experience the scenario. At high speed, controls and habit slow AoA changes reduce to he risk. Heck, the 1.5G limit might be exceeded to take the airframe to stall at speed.
A software upgrade, not a big deal.
Right. During slow speed flight the airplane will naturally be at a higher AoA , and therefore closer to the critical AoA. If a sudden pitch up maneuver is performed, such as a go around, the aircraft pitch rate can exceed the rate at which it can respond to enevelope protection, which could lead to a low altitude stall. That would most certainly be deadly. I’m glad Airbus caught this, but to say this isn’t a big deal is treating it too lightly.
I wouldn't say it would most certainly be deadly - as others have eluded to, it requires a number of parameters to be met (including, apparently, a high density spaceflex-fitted NEO, probably at a light weight) while performing a go-around-type maneuver.
Even then, the very core design of the flight envelope protections have significant authority to prevent the situation from becoming deadly. It's likely what was detected simply had more to do with HOW the aircraft was SUPPOSED to perform, which no longer fell within the realm of "normal" as far as A32X handling is concerned (ie. how pilots are trained, what they expect a given input to perform, pitch rates, etc). They need to modify the software so that any variation of cabin layout and type (ie NEO) act the same way for continuity, certification requirements, etc.
Commonality within Airbus products has always been a huge selling point, not just with operators but with pilots as well - I'm sure they're highly motivated to get every element of the NEO to act like any other 320-family AC.
A couple other notes, firstly why it "wasn't caught" - I'd imagine they did extensive flight control and software studies / reprogramming during the NEO design/development program, which was fine (the original NEO cabin layout was not part of the issues being reported here from what I understand). However with the introduction of SpaceFlex cabins later on, I'm assuming the same level of aerodynamic and control studies weren't done.
Another note is the fundamental (and physical) design of the aircraft versus the MAX, since many in this thread continue to draw direct comparisons between the two aircraft. From an aerodynamic point of view (as far as I understand it) we are talking about VERY different issues here. The behavior is similar, but the root cause is not. The engines on the NEO are in a nearly-ideal location, both CG and vertically as far as center-of-thrust is concerned (as opposed to the MAX). This issue w/NEO is from a true CG / weight location problem (again, due to layout). Applying TOGA power at slow speeds (regardless of load/CG) on the MAX will result in (as I understand it) a VERY unexpected pitch-up, even with MCAS the plane still does this, it just "has a system to correct it" kinda. Conversely, on the NEO you need to have the right plane in the right cabin configuration at the right weight to encounter this, and even then there are control systems in place to prevent loss of control - the behavior itself is very undesirable though.
As far as fixes are concerned, the two aircraft are on different planets here. The NEO has all the computing power and redundancy it could ever need - it already calculates and protects AoA issues with triple-redundancy on both CEO/NEO. Beyond the flight protection aspect, the very handling and behavior of the plane is FBW, thus if ANY condition during any regime is undesirable, you can tweak the behavior in the core FBW and not rely on a protection in the first place.
When Airbus implements this fix, technically a SpaceFlex high-density NEO can execute a TOGA/missed at light weight and act EXACTLY like a CEO/NEO. THIS is the definition of grandfathering and commonality as far as I'm concerned.
Conversely, regardless of whatever MCAS fix is eventually implemented on the MAX, the plane will always
exhibit that pitch behavior. They're just concerned about protection afterwards. That's a different definition of "grandfathering" in my book, but oh well. It should work fine when fixed.
Unfortunately the MAX engineers have NONE of this capability; not the sensors, computers (both number and computing power), nor the ability to alter the actual/core flying characteristics in a flexible way - you simply have add-on things to change how it flies, and it's more of an on/off switch in terms of behavior and certification, ie focus on disconnects over complete redundancy.
That's the difference between the two, and that's also why it's taking Boeing so long to get it fixed (obviously they're also being scrutinized to an extreme degree as well, which is certainly not helping). Apologies for the rant - I've wanted to vent this for a while.