I get it, and tbh the probability of Oda doing this is disturbingly high imo.
I just don't feel comfortable with pairing an 8-year old with a 28-year old, even if both of them physically are on the same level. If it was real life, it would be really disturbing - imagine an 8-year old going into coma, then waking up 20 years later, do you consider them an adult?
I understand it is fiction, but still Yamato feels like an older sibling at this point. I hope it stays this way.