He was great last season (Manly's 2nd highest in line-break assists and highest try-scorer), and if he continues being one of the most important attacking weapons on the field, I don't know why we'd be happy to see him move on.
That is of course if we see a drop in form, and Tommy T just can't be contained on the wing anymore. But this will be Tommy's 1st full season, and if both are playing great, then they could do the ole 'Mini RTS switcheridoo thing' for '16 and '17.
I feel our best chances for a premiership tilt will be in '17, but we will need Snake and Killer for one final season to potentially get the job done.