After Yonny Hernandez testing with Tech 3 Yamaha at Sepang Wintertest there was no confirmation that Yonny will replace Folger. That still leaves the seat vacant.

Possible candidate is Hafizh Syahrin, currently Moto2 rider with SIC Racing Team. But it could all change come Buriram Test.
Speaking to MCN, Herve Poncharal, at the Sepang circuit, confirmed that the Malaysian rider’s name is now on their list of potentials but was adamant that a deal is still far from confirmed and nothing has been decided by far, because there are different priorities from the sponsors.

Syahrin has spent five seasons in the middleweight class since joining the Grand Prix paddock full time in 2013, taking a best finish of ninth in 2016 and scoring two podiums in 2017, at Misano and Motegi.
For now it is still a rumour with Hafizh Syahrin as one of the prime candidates, but we all wish that the 23-year-old becomes Malaysia’s first rider in premier MotoGP class.