Since you're using basketball-reference.com, it's worth noting that there is a way that you can actually use data from the site to account for projected future stats for a given player.

They use similarity scores (see here for Michael Jordan for example) to match each player with 10 additional players with similar career arcs. You can then use average over those 10 players for points scored for subsequent seasons (using only players that actually played subsequent seasons, which would fit the assumption that Michael Jordan played additional seasons). This would give a rough approximation for how many points Michael Jordan would be expected to score if he continued to play, based on career arcs of similar players.

While it's not perfect, it's far better than assuming that players would continue scoring at peak levels indefinitely.