Not this again. WHS HighSt and WHS Airports/RailStations are two separate divisions and both are profitable divisions. One half really isn't propping up the other. The High St division is in managed decline and shops are being closed piecemeal as and when they no longer meet the targets required. The rail/airport foreign side is continuing to grow.
WHS own a lot of their High St stores so they're not paying ruinous rents to landlords unlike other chains which have fallen which means their High St stores are more profitable/less loss making. They're also "managing the decline" by not spending a fortune on renovating the High St stores, hence why many of them are now starting to look shabby - again, not spending money, so they can keep them open for longer. They have also incorporated small Toys R Us outlets within many High St branches to continue to drive footfall into their shops, along with taking in many Post Office counters in towns where there's no longer a "crown" post office. High St stores are also often the "last man standing" in terms of newspapers and magazines and they're often the only "go to" place for more specialist foreign and obscure hobby/interest magazines that you can't buy in supermarkets, again, driving footfall into their stores.
Maybe in 10 years or so, their High St stores may well have all closed or radically reduced in numbers, but as I say, it's "managed" decline, so they're not trying to keep loss making stores open by propping them up with profitable high street stores, hence the long term closure/rationalisation program. That's a direct contrast to other chains like Woolworths who tried to keep all stores open, even loss making ones, which caused the entire chain to collapse.
WHS High Street aren't disappearing any time soon.