I don't think that any other coin would ever get accepted in any shops.The main reason is that bitcoin has faced many critical situations and challenges from governments and bankers and has carried out huge volume of transactions.But other coins have never faced such issues and they have never proved themselves that they would withstand such problems.Also,i think that they would never gain universal trust as what bitcoin has got.No coin could replace bitcoin by having just a single feature of low transaction fee.
I think that 99% of the challenges have still yet to be faced from governments and banks. 99% of the public is only now learning about cryptos in general, let alone Bitcoin so I think the picture that you are describing has not yet been seen and probably won't be seen for many years until all is said and done.