I don't think using Doncic as a PG will create that many matchup problems going forward because it seems that Point Guards keep getting bigger and bigger coming into the league. Over the last 2 years, 6 of the 8 PG's chosen in the lottery are 6'4 or taller. Ben Simmons is 6'10, Lonzo Ball is 6'6, Frank Ntilikina is 6'5, Markelle Fultz, Jamal Murray, and Kris Dunn are all 6'4. The other 2 are DeAaron Fox and Dennis Smith Jr who are both 6'3. Most teams have at least 1 PG who is 6'4 or taller and there are 10 teams right now who start a PG that is 6'4 or taller currently.
While Doncic will have a few inches on most opposing PG's, it won't be what it would have been 10 years ago when 6'4 or 6'5 was considered a big PG. Most teams will be able to switch off easier to a defender that is his size. Using their wings to cover him and moving their PG onto Booker or Warren/Jackson.