So it is a matter of time before Shopee review the use of cryptocurrency for direct payment as alternative to fiat.
So the adoption is already on whether Shopee is accepting Bitcoin now or not. They won't have choice by the time another big name opens up within their jurisdiction and sells same kind of stuff they do while accepting Bitcoin. Of course they would begin to lose customers.
No business or store will lose customers just because they don't accept bitcoin in their business, while their competitors do. The future and growth of a business depends on their products, services...and has nothing to do with bitcoin. Don't overestimate the importance of bitcoin, as bitcoin is just an alternative payment method if adopted, not the only payment method. It also has nothing to do with the business operations of those companies.
Using bitcoin as a payment method is just an option because it was created from the beginning as an alternative, not a replacement for any system or currency. This will depend on the decision of each business as well as the legality of each country.