Honestly I don't think Pacers will have this opportunity again next season. Like you guys also mentioned, they won't have Haliburton in the first place because of achilles injury. 
With whom they are going to fill his space? Siakam can't take full responsibility there. He is good but not enough to carry the team by himself. We saw it in the finals while Haliburton was injured.
With whom they are going to fill his space? Siakam can't take full responsibility there. He is good but not enough to carry the team by himself. We saw it in the finals while Haliburton was injured.
Being beaten by OKC had nothing to do with Haliburton being injured, just look at game 6 where he had 4 points in 34 minutes.
I think they can still be a good team, even without him. He is solid but not yet the guy you can rely on all the time, he showed it in the finals where in 7 games (or 6 because of the injury) he only had more than 20 points 1 single time.
Losing Miles Turner for me personally will have a bigger impact and unless they find a good replacement for him it MIGHT become a long season.
Speaking of Turner, I also believe that losing him has a great impact as well. Losing Hali for a season because of injury is already a bad thing, but losing your main center and has been in your team for a decade, and going to your "rival" team makes it even worse. On the flip side, they signed Isaiah Jackson to a 3-year $21M deal to fill Turner's shoes and he will be their starting center next season, but I don't know if he can do it TBH. As for Siakam, I expect him to be their number one guy next season in terms of offense, but the Pacers are pretty much balanced as a team so many will help him still.