Blizzard just revealed some rule changes for WCS 2018. With the announced changes, young players like Reynor and Clem are allowed to sign up for WCS events, as long as they are 16 before the event begins.
In addition WCS 2018 will have a less top heavy prize money distribution and WCS points will be awarded to the top 32 instead of the top 16. This means that players who are elminated in the ro32 will still get 100 points for their efforts.
The age restriction change especially will make many fans and players happy, as the discussion about the age restriction has been ongoing on community forums and social media.
Clem and Reynor have been turning heads for a while with great performances in online competitions, but have not been able to play in the WCS due to their age. According to the old ruleset, they would've been unable to play in the WCS 2018 as well, despite them reaching the age of 16 later this year. Thankfully they can now look forward to competing in the most important sc2 tournament circuit, once they turn 16 in April (Clem) and July (Reynor) respectively.
Official WCS 2018 Rule Book