Imo oda reintroduced smoker to early post time skip. He like won't make a big appearance till eos as he to weak to effect the crew. He had a garp like portrayal where he'd hunt down the sh's but he to weak to do anything if he ever caught them anyways. I think if he reintroduce smoker currently and made him strong enough to challenge luffy he'd be a great secondary antagonist as sh's would always be on a race against time with smoker hunting them down. Even needing sanji or zoro on some occasions trying to hold him off with the sh's escaped and luffy was recovering from a post arc fight. Like imagine if at the end of wano sh's had to party early and leave quickly not fully recovering as smoker was right behind them. If smoker a bunch of marines and green bull all arrived on the island with the sole goal to get luffy.