Keep in Touch is generally a way for McKinsey to maintain a relationship with candidates they may want to engage again in the future. The precise reason someone is invited can vary.

It is reasonable to view it as a positive signal, but not as a promise. This overview of the McKinsey Keep in Touch program explains how to interpret it.

Your next recruiting outcome will still depend on the profile you build and the role available when you re-engage. Use the relationship, but continue developing independently.

The safest mindset is: better than a cold application later, but nowhere close to an offer today.

That last line is exactly how I'd view it. Warm relationship, not guaranteed pipeline.

I got KIT after undergrad and later got an interview through MBA recruiting.