Your best audience doesn't transfer
The customers who carry your marquee category cannot be counted on to carry the next one.
Return customers drive between 65% and 77% of launch-week demand regardless of gross sales. That base is powerful and it is category-bound — it showed up for devices and did not show up for anything else.
So a new product outside the marquee category needs an acquisition plan, not an email plan. Assuming the existing base will float it is the most expensive assumption available.