Oh boy, this is my field! Let me go do some math and I’ll get back to you in a couple hours.

EDIT: This is probably going to take a day or two. There’s a hell of a lot to break down here.

Probably a long time. Humans are fairly resilient just gotta follow the rule of 3…

3 minutes without air 3 days without water 3 weeks without food

Equals dead. (Roughly give or take depending on environmental factors.)

The whole milk is really making this plausible

http://www.milkfacts.info/Nutrition Facts/Nutrient Content.htm

Probably live for years and years. Milk is sufficient for a baby to grow up after all.

The cereal is probably going to make the milk less healthy then milk alone. Carbs, and anti nutrients, and fibre - reducing how much nutrition you can absorb from the milk

I know i would go crazy eating the same bland flakes

make it the total raisin bran variety and i could probably handle it for at least a month or two.

Long enough that it’d be hard to rule diet as your cause of death. Your biggest consequences would be low energy and a weakened immune system. Not a great place to be, but you’re not gonna be so weak that you fall over to a stiff wind. It would take an untreated illness like the flu or pneumonia to actually kill you.

Probably long enough to make yourself slightly unwell, get a test from the doctor, and sue the company for not providing you with all the nutrients they claim! Lol

Totally dont’t know

It says it has all the vitamins you need but probably not all the amino acids, but idk

I would think for a very very long time until some vitamin deficiencies caught up to you.