I think the issue with England going forward will be the other opener and a number 3. It's a lot to ask Taylor to step up to 3, considering he's literally just been put in the side. Add to that Root not looking great against the new ball and they should be kept at 4 and 5 for me. I think the option of bringing someone like Compton in to open would be sensible, the only problem being that he's not going to score that quickly, which seemed to be the issue last time. Personally, I'd like to see Hales come in and bat at 3. Someone who can be more aggressive, but with hopefully a bit of protection from the new ball.
Ali is the problem, in that it's hard to fit him in the side without having him at 8, which is a bit silly, with his ability. That being said, Stokes being injured could solve that problem (although hopefully he's not done anything too serious) in that Ali could bat at 6, with 4 pace bowlers to back him up in SA. Would be a good way to get a player like Woakes into the side too, without putting too much pressure on his batting.