Can we hope for a Komplete Kontrol A88?

Doubt it. An 88 key keyboard is really only suitable for more proficient users who have the room and can justify the space, typically they can justify the cost. Too many models would mean too much inventory, I think if people really need the 88 keys, they will invest in the S series or just make do with 61 keys. Just doesn't make sense to have lightguide and piano feel 88 key in a "cheaper" version without screens to save a couple hundred bucks.

No, I said "Typically", which is true as most bedroom and small producers dont have the space or need for full range, usually those that are trained and have actual skills which they usually choose the right tools and sacrifice for the extra cost.

Well I play and I only have a 61 key version because I also play other instruments, prefer the synth feel over weighted for compromise and simply do not have the justifiable room for something that massive. Have managed just fine with 61/67 keys for 25 years.

An 88 key version exists and as mentioned, most people with a need for that size will typically want something that has a premium feel. If the A series was 88 keys, it would not have the semi weighted keys as that is a large chunk of the overall price, not to mention a larger keyboard needs better engineering. Then you have the limited pedal inputs and also lack of after touch, no MIDI connectivity to use with hardware.... lots you would give up in function for something that takes up 1/3 your room space.

There are fewer people with a need for 88 keys and probably even fewer that would choose to not have displays or lightguide especially since the LG would be the main point for the 88 key model other than offering a full range.

By all means you can certainly hope it will happen, I just don't think it's ever going to be a thing.

I know of a few models yes (tho you will easily find far less 88 key models out in the wild than any other key version, for all the reasons I have already stated), but do these manufacturers also have 3 other lines of keyboard models with 25/37/61/88 key models in each line?

All I am saying is that in a general sense of the word (not to be taken to the literal nth degree) the users looking for 88 keys can generally afford/justify the extra cost for a premium model and most 88 key models I have seen are from the higher end options from manufacturers... You won't find an 88 key version of a korg nanoKey for instance...

Hope, prey and dream for a cheap 88 key model sure, I'm just adding a realistic argument to not place your bets on it happening any time soon.