I recommended that people build a niche store so they can keep launching relevant new products as a hedge.
I said the advice depends on the timeframe being considered. The post does not specify the risk being hedged, the timeframe, or which niche or products were under discussion.
How you hedge against that imo is to build a niche store so you can always launch new relevant products.
Related: niche research terminology and advice, store strategy metrics and lessons, dropshipping as launchpad to brands