I find this proposal an interesting thought experiment, for sure, but replacing all the vocabulary except the grammatical words seems more likely to me than replacing just the grammatical words and the grammar and retaining all the other vocabulary. Are there any other cases of the grammatical words being replaced while the rest of the vocab was left intact?
The fact that there was so much and such dramatic change happening that either of those possibilities are reasonable suggests to me that we're not going to get a definitive conclusion anytime soon.
The fact that there was so much and such dramatic change happening that either of those possibilities are reasonable suggests to me that we're not going to get a definitive conclusion anytime soon.