The Samsung Galaxy S9 lineup is more than a sure thing at this point, especially with news coming out that the devices have been certified by the FCC.
Although no additional information came out from this certification, we do know their model numbers: SM-G960F (for the S9) and SM-G965F (for the S9 Plus). Unfortunately, we will not get any other details out of this filing, since Samsung submitted it back in November 2017. At that point, the S9 was probably just a concept.
More importantly, we need to tune in to whether or not the Galaxy S9 line will debut at CES 2018, or if it will come earlier. Nevertheless, Samsung will definitely announce something at MWC 2018, or even put up a special event for the debut. For now, just tune in to any future news regarding the device.