As someone who is familiar with both, they're slowly becoming different languages. The pronounciation is radically different, the grammar has already differed in some pronouns and conjugations (e.g. gerund) for a long time, vocabulary differences are slowly accumulating and we'll see how orthography continues to evolve. We're not quite at the Scots vs. English point yet especially because of shared media but it won't surprise me if it doesn't take too much longer to surpass that.