Suarez played as a LF last season and does it pretty well. Playing a false 9 doesnt mean you have to exclude a striker. On paper he is a RW, but he still plays a free role anyway. So I dont see why he would have trouble playing a false 9.
Regarding Malcom-Messi-Dembele, it can work just like how Coutinho-Messi-Dembele looked promising as well. It is extremely fluid and could provide Messi with options and intensity, rather than having an extremely static central striker. You can have a box-to-box like Vidal to put an extra man in front and it would work just fine. If you have someone like Raktic then forget about it.
Not sure how being a false 9 in Barcelona is not effective unless you have anything to back that up.