What happens when transaction bandwidth is exceeded? A search for definitive information turned up literally nothing, so, what happens when transaction bandwidth is exceeded for an extended period?

After a period of two weeks (default) transactions are dropped from mempool, if this continues for three months then all transactions from weeks one through eleven will need to be resubmitted a) when the load on mempool dies down a bit or b) with higher fees excluding some other transaction in its place.

I have seen mempool with over 50,000 transactions for many days in a row, perhaps weeks, so, should this actually be called a quasi-payment system where it is possible any given transaction may eventually be forgotten about if the user does not keep on top of it?
A search for definitive information turned up literally nothing, so, what happens when transaction bandwidth is exceeded for an extended period?


The same thing as always happens: miners decide, at their own discretion, which transactions to include in their blocks.  Most likely they will choose those that have the highest fees.  Transactions that don't go in the blocks remain unconfirmed.  There is no special handling for such a case.


  After a period of two weeks (default) transactions are dropped from mempool, if this continues for three months then all transactions from weeks one through eleven will need to be resubmitted a) when the load on mempool dies down a bit or b) with higher fees excluding some other transaction in its place.


That's correct.  If the user still cares about having the transaction confirmed, they (or their software or their wallet provider) will need to do one of those two things.


  I have seen mempool with over 50,000 transactions for many days in a row, perhaps weeks, so, should this actually be called a quasi-payment system where it is possible any given transaction may eventually be forgotten about if the user does not keep on top of it?


It's true that Bitcoin does not provide any guarantee that a given transaction will ever be confirmed, and it never did.  That simply isn't a design feature.  Feel free to call it a "quasi-payment system" if you like that term better.