So at a minimum, dropping kanji would mean the language needed to develop a system for where spaces go (which is less trivial than it sounds IMO). But also it would need to abandon a lot of homophones or find some way to disambiguate them. It could happen I guess, but I'm not sure how it could happen gradually.
It's a bit easier for Korean as it has far more available syllables (so fewer homonyms), but you could easily imagine these languages making different tradeoffs and ending up in different places.
I think at some early point most Japanese learners (that don't already know a Chinese language) think kanji should be dropped. And at a later point I think most would change their mind as the advantages outweigh the disadvantages.
At least, that's the reason why I prefer still having kanji around.
This was indeed the Communists’ original plan, but the real story is more interesting. Before taking over the country the plan was to replace characters with a pinyin-like system Latinxua Sin Wenz[1] and a whole generation in the north was taught to read this. After 1949, Mao was talked out of Romanization by none other than Stalin, who told him the Chinese language deserves its own script. Pinyin was designed after that, officially as a teaching tool, but probably by people who secretly still believed in more radical writing reform.