Besides your "general" ranking can decrease, you will gain more targeted users, i.e. reputation for that specific country.
Country-code top-level domain names are one of the elements that Google uses to determine a website’s targeted country.
If Google is aware of the country targeted by the site, they will use that information to improve the quality of search results improving visibility to the users of the country, and decreasing it from the users of other countries. That is what ccTLD are really for. If the site targets international users or do not want to be associated exclusively to that country you should keep the generic
ccTLDs are a strong signal that your site is intended to that location to both
Making that change, will end up in having more users from that country and probably decrease visitors from other countries.