Being clinical doesn't necessarily matter. The more chances you have, the more goals you tend to score. If you make more chances for yourself, you will score more goals. Salah's movement is maybe the best in the world. He will get a lot of chances.Well, he's already seen a massive dip in goalscoring form since his anomalous breakout season. He just isn't really that clinical and his first season at Liverpool still has a lot of people hoodwinked.
He regressed to his mean last season and if he stays at his natural level, he'll be trounced by Kane, providing the latter can stay fit for most of the season.
(But I ultimately agree with your question. I don't see why Salah should drop off in scoring much more than he already did last season.)
If everyone stays fit all season, the only players I can see giving Kane any grief are the City boys through sheer volume of chances. That team creates so many chances that a profligate striker could hit 20 with ease -- and they have much better than profligate.