As Substack pivots from VC driven growth at all costs to needing to actually be profitable, they will slowly chip away at every one of those facets: domain will get more expensive (likely monthly), email list will be locked down or paid, content export, and even payment portal likely changes to be through them.

They have to justify a valuation at some point and it will happen. This happens with every VC company, they grow because they do unsustainable things, then pivot to ruining the platform.