As stated storage in the cameras are a plus. But keep this in mind. If your NVR also is your POE injector then if they take the NVR all recordings stop. If your cameras use an external POE injector or a POE switch, then you will still be recording.
The amount of resiliency can cover a wide spectrum, but only you can decide what path you will follow.
Agree, it really comes down to finances, resources, and the willingness to commit on a solution.
Possible solutions and how to enhance the same.
1. Edge recording only (ER) local first
2. ER & NVR (local first)
3. ER, NVR, IVS (local first)
4. ER, NVR, IVS, PtP -> PtP offsite IVS / NVR / NAS (Local / Offsite)
5. ER, NVR, IVS, PtP, Cloud (Local, Offsite Managed, Cloud UnManaged)
The benefits of PtP is a dedicated connection which enhances privacy and security which you have full control over. The downside is the initial upfront costs for hardware, installation, ongoing maintenance, and energy consumption costs to power the same.
The benefits of a P2P (Cloud Solution) is very low initial cost as there is no initial hardware purchase, maintenance, or long term energy consumption to power the same. The downside is a constant internet connection and if you have bandwidth limits or unreliable connectivity this isn’t a good long term solution.
Many cloud based solutions have no ability to rotate out (old data) and will simply max out and stop ingesting the same. So active monitoring is paramount if such a solution is in place. The average consumer will have to accept the initial savings from the purchase of hardware noted up above but replace the same with a endless monthly storage fee!
Depending upon the person that doesn’t pencil out over the long term - in terms of finances. Yet others will accept the same as there’s very little maintenance, management, and energy consumption to worry about.
Fail over, Backup, Resiliency all require a clear goal / objective. How you get there comes down to finances and committing to the same.