Hi Jason,
ASA OS is going to be maintained. There is no such roadmap announced where they are making ASA OS as end of life. They are keep releasing new versions & releases regularly. ASA is also available in new Firepower platforms which also indicates that it is going to be there.
It is the ASA 5500 series hardware platform itself that is going to be obsolete. Most of the products under this family is already announced EOS and may not support future/new releases of ASA/FTD software code.
Which ASA product you are using in your environment ? You can start planning to move from ASA5500 to Firepower with ASA or FTD software code in future. Below are the end of sale/life notices for ASA Platforms:
https://www.cisco.com/c/en/us/products/security/asa-5500-series-next-generation-firewalls/eos-eol-notice-listing.html
