Google's Instant Search feature is being discontinued as Google aims to streamline its search design for all platforms. The feature is supposed to be disappearing from Search on mobile web and desktop as of today, so if you were used to seeing this as you typed for stuff on Google using your mobile or desktop browser then you'll likely notice that it's disappeared. Google Instant Search isn't to be confused with the automatically populated suggestions which will still show up in a dropdown list below the search box. These are still visible and Google isn't getting rid of these suggestions as it will still provide users with a way to get to the search results they're looking for as fast as possible, which has always been Google's goal, to deliver content to users as quickly as it can when they go to use Google to search for something they're interested in or have questions about.
While some users may feel that Instant Search was an important feature to have to ensure that their searches are completed more quickly, according to Google many things have changed since 2010 when Google first introduced it to the public. Some of these changes include the way people are completing their searches and what platform they're using as well, which as Google Notes, for the majority of users now seems to be on mobile devices, citing more than 50 percent of users looking to mobile to perform a search which has vastly different input and much smaller screens than what most people may be used to when searching with Google on desktop.
As mentioned above, Google's goal is to streamline the design of search across all of its platforms as it wants things to look more fluid visually, and this just so happens to include getting rid of instant search as it doesn't translate as well to mobile devices these days. Google hasn't mentioned how it plans to continue improving search and making it so that users can search for stuff as quickly as possible, but it's likely that the company will share more details about what it may be replacing instant search with (if it's replacing it at all) in the future.