The "chipset" (APQ, PMIC, WCN, WGR and memory) will be around until at least 2025, possibly longer. Qualcomm has commited to being able to supply these components. The 410c DragonBoard has many other components onboard (USB hub, MIPI-DSI to HDMI, resistors, capacitors, inductors, etc.) We have mad every effort to ensure that all of these components will be around but we do not have control of the third parties. If a component does go obsolete we may be forced to (slightly) redesign the 410c to make changes. We may also choose to add improvements to the 410c at the same time, so there may be revisions to the design over time. The 410c is a community board and we will make best efforts to carry the design through for the long haul.
If you need a guaranteed supply of boards for your production line, you are best to talk to one of the many third parties building boards/systems/SOMs, such as Intrinsyc, InForce Computing, eInfochips and many others.
Full Disclosure I am an employee of Qualcomm Canada. Any opinions I may have expressed in this or any other post may not reflect the opinions of my employer.