I think this is a pretty good analysis.
For me, however, the question is whether the £5/month Monzo receive from (what I suspect will be a relatively small) group of users, is worth more to the business than number of new sign ups and fullmonzo conversions that might have been achieved had all these features been offered in the basic current account.
Worse still, I fear that Monzo will now be forced to keep a gap between the Plus and Basic accounts, which is likely to narrow the gap even further between the Basic account and Monzo’s banking rivals, and cause long term damage to sign ups and fullmonzo conversions.
Monzo would surely do better to make their 4 million regular users profitable, rather than focusing on a tiny fraction of Plus customers.