Hi Dhiren,
That scheme should work. Keep in mind that the state of CS will be dependent on the state of the demultiplexer. A couple of options would be to place pullups or pulldowns on the address inputs (to create a default condition), or pullups on the ADS1148 CS pins with another control line to the demultiplexer to disable the output. I prefer the latter option so that I can completely disable the outputs of the demultiplexer so all CS will be high when not communicating to the devices.
Best regards,
Bob B