The franchise, the largest by number of passengers and composed of four previously separate rail operations, is run by a joint venture between the UK's Go-Ahead (GOG) and France's Keolis. But its Southern rail services are suffering due to significant infrastructure improvement works impacting London Bridge station as well as its running dispute with unions over the role of guards.
The proposal by Mr Khan suggests the franchise be run by Transport for London (TFL) because of the experience and high levels of service it delivers running the London Underground and Overground services.
But should the companies behind the joint venture have their mandate to run the services removed from them?
If they did, it's unlikely delays would be completely eradicated. After all, a report by MPs shows predictions of the 10,000 extra minutes of delays due to the work around London Bridge per month were extremely conservative compared with the 10,000 minutes per week reality.
This has, of course, been exacerbated by the head-to-head with unions, but Go-Ahead has undertaken what it called in its results, published in September, "one of the largest driver recruitment programmes ever undertaken in the industry". The flip-side of this, as commuters using its services may well be aware, is that this training takes some 14 months, so the ranks of drivers are not going to swell immediately.
Not only this, but it would seem unlikely for the government to strip a privately-run business of its franchise. Govia is, at present, making a small loss, yet Go-Ahead still contributed £222m to the Department of Transport.
The agreement between the franchisee and the government also protected it "to a degree" from industrial action, chief financial officer Patrick Butcher told Investors Chronicle at the time of the results. So, unless the company is seen in the eyes of government as being particularly unwieldy in its negotiations with unions, expect things to stay as they are.
As a commuter, this probably doesn't make you feel any better, but as an investor, you'll be hoping such drastic action isn't taken given Go-Ahead's rail revenue jumped from £1.8bn in 2013 to £2.5bn at the end of its 2016 fiscal year on 2 July - a decent chunk of which came from the Govia win.
