Yes, they will still need a TA, because those kids who need 1:1 need 1:1.
It is entirely possible that they can never be left unsupervised.
In which case they are not at all an 'extra pair of hands' in the classroom.
It's not all those adults which are a negative thing. It's the exact mix of SN kids you have described. One with profound difficulties, one with ASD and one with behavioural probelms.
Have you any idea how bad 'behavioural problems' have to be before you get a statement with 1:1?
Same with profound difficulties and ASD. Very few kids get these 1:1 statements. These kids have severe additional needs - and at least 2 of them have severe behavioral problems.
So, they might be noisy all day, they might run around the class all day, they might hurt others, they might have massive meltdowns in class.
You think a class with 3 children like this in it is going to be pleasant for your child?
Last time my child had a meltdown some of the other kids were so distressed that the SENCO rang their parents to tell them why their child was upset. And my child is the most mild end of the spectrum you can imagine. What if you get meltdowns like that 5 times a day?
If there was 1 child with a behavioural problem, 1 who was visually impaired, and 1 who with CP, that would be very different to the mix you have described.....