DNA Essentials License is, essentially, a "tax" or a "levy" -- Everyone who buys Cisco kit is going to pay for it (whether they have a DNA appliance or not).
The most "basic" license anyone can get is the Network Essentials License and there is nothing else "lower" than that.
When the DNA license expires, and there is no DNAC appliance, do not worry about it. Let it lapse and nothing will happen.
Regarding maintenance, i. e. RMA faulty switch, read the 9200 Data Sheet and scroll down to the Warranty section:
Cisco Catalyst 9200 Series switches come with a Cisco Enhanced Limited Lifetime Warranty (E-LLW) that includes Next-Business-Day (NBD) delivery of replacement hardware where available and 90 days of 8x5 Cisco Technical Assistance Center (TAC) support.
Your formal warranty statement, including the warranty applicable to Cisco software, appears in the information packet that accompanies your Cisco product. We encourage you to review the warranty statement shipped with your specific product carefully before use.
Cisco reserves the right to refund the purchase price as its exclusive warranty remedy.
In regards to software downloads, read "Cisco Catalyst IOS Software Update Program for Cisco Catalyst 9200/X, 9300/X, 9400/X, 9500/X and 9600/X Series Switches" and scroll down to the Program Summary section:
● Free critical updates:
◦ Free critical updates are available to the original customer for up to 1 year after announced end-of- support. These critical updates maintain the compliance of the Software with published specifications, release notes and industry wide compliance.
◦ Free vulnerability and security updates are available to the original customer for up to 3 years after announced end-of-sale.
◦ No support contract is required to obtain these software updates.
● Free major and minor releases:
◦ Free major and minor release updates are available to an original customer moving from one release to another within the same perpetual license level (i.e. Cisco Network Advantage or Cisco Network Essentials).
◦ No support contract is required to obtain these releases.
