@swscco001 there is no notification of how long it will still be supported AFAIK, I expect Cisco will continue to support it whilst there are still customers requiring it. If you require further information I would recommend speaking to your Cisco Partner or Cisco account representative.
You should be able to disable SHA from where ever it is used in your configuration and use something more secure. SHA-2 and other next generation crypto has been available for a considerable period on ASA software, so there is no reason why you cannot use more secure crypto algorithms.