I suspect a number of things will happen at the new AA under Parker's leadership, including the following:

1) Mixed fleets are here to stay. With an airline as large as the New American there will be little cost savings in rationalizing the mainline fleet under one manufacturer. I suspect with A350's and 787's coming down the pipeline.
2) Three-Classes of service internationally is likely to be eliminated to allow greater fleet flexibility.
3) AAdvantage will probably the surviving brand at the New American, but will probably be dominated by the best practices from the Dividend Miles Program.
4) Horton's domestic IFE will be the first thing on the chopping block as it probably costs more to install than generates in additional revenue.
5) Likely the AA A321 3-Class Premium service will go away in favor of a simpler 2-Class arrangement that can be supported by US's existing A321 fleet. Niche products are not necessarily Parker's greatest strengths and may be a huge source of expenditure for the existing AA.