I think this step will not run long-term online shopping portal must use both methods because mobile app shopping is for limited mobiles customer and not every customer will install app.
Also mobile OS /Virus/Hang problem and safety issue also there and they have multiple option available in current market as I told in my last blog on #Online Shopping vs Mall Shopping.
Age group also factor in app shopping Young generation want something different so they are not buy cloths online. In Mall they get trial & buy facility this is also one factor and above 40 to 60 Age customer not recommend on app buying they prefer on desktop buying because in desktop they got max resolution view also other websites similar option comparison pries, discounts. not every person use mobile for online shopping even metro city people not recommend for mobile app buying first they prefer desktop buying.