It's impossible to say for sure, because we don't know all the history of the unit. Each piece of hardware has it's own, unique material properties and imperfections, added to usage degradation. For example, CELL processor "X" and CELL processor "Y" will have different, tiny, limits in thermals and performance, even if they were made from the same silicon waffer.
Your unit may have more years of life because of the maintenance done, but if you happen to get high temps because of a bad heatsink contact or degraded fan bearings, then the console may start getting heat damage (leading to YLOD or worse) and you will be unable to notice it.
As the factory fan curve always run at the same speed, you will never know if your console is having thermal issues because the fan will run quiet all the time (unless you check the temps often by touching the console, which is not a precise measure and a real pain to do without having WebMAN MOD or some kind of homebrew app).
The CELL is the thing that produces the most heat, but it's not the main suspect of a PS3 dying. Also, if your CELL was delided and reballed then the joints will surely make contact with the motherboard (if the reball was done correctly).
Rest assured that the CELL will not kill your console if the heat is exhausted as expected.
There are alternatives for this:
- Use DualBoot FW (a special FW that is exactly the same as OFW but leaving the update FW validations disabled, allowing to install CFW in the future).
- Disable syscalls (WebMAN MOD and Evilnat's CFW 4.90 have options to disable syscalls, reducing the risk of getting banned).
As long as you don't use RTM tools to cheat online, run modded EBOOTs or insult people over messages/voice, you won't get banned.
The ideal situation would be to have an online-only console, with OFW, and another one with CFW for everything else. But it's not cheap.