@JohanElzenga is correct. Adobe does not announce feature releases in advance. Major new releases usually happen roughly this time of year (Lightroom 8 for mobile just released.) Subject masking is still the option for masking people on mobile. A workaround is to use the people masking on desktop to create all the masks, then you can open those cloud files in mobile to edit further. All the masking will carry over to any device once created.