BitAssets depend on the existence of centralised exchanges for their price feeds. If the market moved away from centralised exchanges to decentralised exchanges for certain assets such as bitcoin, do the corresponding bitAssets become obsolete?
No, the price feed would come from the markets on the DEX that trade against bitcoin gateway tokens instead. For example GATEBTC trading against BTS on the BitShares decentralized exchange can give us BTS/BTC price feed for BitBTC. Later we would have USD gateways as well which would trade against BTS on our exchange.
Now in that case the counterparty risk has moved from the exchange to the gateway provider, but we can sufficiently decentralize the gateway provider for cryptocurrencies through delegate multisig. For fiat gateways there isn't much you can do to reduce your counterparty risk exposure other than not holding too much or for too long (just enough for the order books and until your order is matched).