[toast0]

> After more than a decade at large sw companies, I can count on one hand the number of migrations where the legacy system was ever able to be turned down.

If part of the plan wasn't to run a v1 shim on top of v2 to handle legacy users that won't migrate, v2 almost certainly doesn't meet the needs of v1 customers and it's not a question of 'migration' it's a question of ending a product and releasing a similar product.

Sometimes that's what's wanted and needed, but often it's not, and then it's a surprise that the v1 users want their needs met and it's hard to say no to paying customers, but nobody signed up to run two products forever.

[sjf]

I’ve seen this happen in situations where the migration is totally invisible to users. My last team is five years into an opaque database migration that seems to only expand in scope. It’s just a symptom of the migration being more difficult than originally expected usually combined with losing momentum or leadership support. Obviously no one originally intends to keep maintaining both system indefinitely.