k i went to wiki
people do keep champagne 
There is a debate about the aging of champagne. Champagne's
freshness has contributed to most people's impression that it
should be enjoyed soon after purchase. Vintage champagne is often
put aside to be enjoyed years after its release. As champagne ages,
it deepens in colour and often develops bready, caramelized
flavours and aromas.
what about the fizz?
