How many investment properties is too many?

[TygerTung]

Dear friend of mine has been a tenant in the same property for 26 years. She has just been given notice to vacate because the LL is selling up.
Imagine the shock that must be.

That must be absolutely awful - especially now.

It shouldn't affect the landlord if she/he has had the property for 26 years as that is plenty of time to pay off the mortgage.