Personally, I think it must be some frontcourt player from the West. Boogie was the only real center in LeBron team, so Denver center Nikola Jokic is the first name which comes to my mind, followed by Paul George, which is not center, but biggest frontcourt name from the West which not selected this year for ASG.
Other poll options include Chris Paul, future HOF, which in different circumstances should be #1 alternate option, but a big problem in CP3 case is the fact that LBJ team already has 5 pure guards. Another voting choice is the cumulative option of some Clippers player because they are .500 team and Los Angeles is host city this year. In normal circumstances, I will put there only Lou Williams name, but because he is a guard, Griffin or Deandre Jordan are also the legit options now.
And because we don't know are substitute player which replacing DMC must be from the West under new ASG rules, I put as poll options Andre Drummond from East as center with best 2017-18 numbers which is not selected, and Miami option, a team with best W-L record without any player selected for 2018 ASG which include guard Goran Dragic, their best player this season, and Hasan Whiteside, their best center. <= this problem is solved
EDIT:
(LINK TO NEW RULES EXPLANATION)
Q: What happens if one of the selected All-Stars gets injured prior to the game?
A: As in previous seasons, Commissioner Adam Silver will select a replacement player from the same conference as the injured player.
Sorry to all who already voted, but I just find this explanation which clears all doubts about rules. Cousins replacement MUST BE from the West, so Drummond and Miami options are not eligible and I deleted it from this poll. If you already voted, please vote again because previous votes from old 6-poll options are deleted (sorry once again)