It is currently happening actually. have you tried betting on directbet.eu? you can see that you can bet which ever coin you have such as dash, eth, ltc and of course btc.
Like the rest of us here i once tried Yobit Dice and you can even use coins that isn't every by the rest. Yobit dice allows you to bet all coins they have listed on their exchange. So yes these alcoins are staying for good and they will eventually be used widely.
Yes, i tried in Yobit dice. All my not so known alts, those who are devalued cryptos I use to bet on Yobit Dice. More alts means more opportunity to use and earb from it.Most gambling sites are now adapting multicurrency to have a wide reach of gamers.