The effect of this phenomenon on rail commuting could be twofold.Prior to the epidemic I attended a conference in York organised by Modern Railways where a speaker from Hull Trains reported on the emergence of a group of commuters characterised by the acronym "****S" standing for Tuesdays,Wednesdays and Thursdays commuters. I suspect that this trend has been reinforced. Carrying on a business wholly on the internet is possibly but Zoom limits. I sometimes need a whiteboard not just to show results but need to demonstrate the logic of how I got them. Brainstorming is another activity I find hard to do. Short distance commuting will revive more quickly than long distance commuting.
Firstly there's the direct impact of the part-timers and flexible workers who take Friday and Monday off or work from home.
Then there is the indirect impact from the reduction in road traffic on Friday and Monday. For those workers who have a choice between car and train, the reduced road congestion can top the balance in favour of driving on those days.
For example (pre-covid) my car commute Tuesday to Thursday took about an hour, and my rail commute slightly longer. I chose rail most of the time. On a Friday the car commute reduced to around 30 or 40 minutes, while the rail journey time obviously remained the same, so I almost invariably drove on Fridays.
I'm probably not representative of most commuters in terms of circumstances, including an extremely uncompetitive season ticket price and a job that requires me to drive for work purposes on some days, but I'd be surprised if I was the only one.