I don't agree, if our current system is what we're looking to play long term we need an alternative to De Bruyne and Silva, i don't think we do at the moment. Doesn't have to be Isco specifically, but he'd be an option.Isco will not be wearing a City shirt, we already have players who can do the job he does who we will be moving on Nasri being 1.
If Silva or De Bruyne got injured, we'd be looking at either having to change our system which is working really well or have big drop-off in quality.