While it's true that eBay pivoted to a more profitable niche, their original niche was still quite profitable: they were a successful IPO and pulling down cash back in the days when most sellers were regular people. So if they're abandoning that market to focus on a more lucrative one, it might [1] leave an opening for someone else to focus on it, and make good, even if not eBay-sized, profits.
[1] With all sorts of uncertainties I haven't properly investigated, such as whether there's been a significant shift that would make old-ebay-style auctions much less profitable today than they were 10 years ago.