Now, I’m not an expert and don’t care too much about the AI side of Halo, so please correct me if I’m wrong. But as I understand it, rampancy in human AI happens after 7 years, when the “smart” AI has collected too much information to handle and they basically think themselves into insanity or power-madness. That’s why the UNSC has protocols to terminate any AI that reaches their seventh year, otherwise bad things happen to anything the AI has access to.
Or, you know, just don’t follow orders and the whole galaxy can pay the price because you got sentimental about a computer program. Nice job mister beef. 
So, according to Halopedia Isabel was commissioned in 2556. If Halo Infinite - and this is very unclear to me, so please correct - happens in 2561 onward, then Isabel only has a couple years left before she needs to go.
I’m not going to theory-craft too much about this, but it’s just another reminder to me about why we need a better connection between Wars 2 and Infinite. The Banished in Infinite, for example, feel like they got the Halo 5 treatment: design changes just for the sake of design changes. Not much continuity.