Law & Order: SVU is about to enter a very exclusive club Wednesday when it hits its 400th episode.

Currently in its 18th season, Dick Wolf's long-running spinoff has defied the odds, continuing to pull impressive numbers even as it ages into seniority not seen in the scripted sphere since, well, the mothership Law & Order reached the same benchmark in 2008.

However, as fans of the franchise already well know, there was one important milestone the original cop/legal drama didn't achieve: breaking the record for longest-running scripted primetime drama. Law & Order tied Gunsmoke's record 20 seasons, but was unexpectedly canceled in 2010 just one season short of pushing past the old Western series' mark.

Now, as SVU inches up in years, the question is whether it will remain on the air to try and break Gunsmoke's record. When asked about a season 19 renewal last month at the Television Critics Association's winter press tour, NBC chief Bob Greenblatt was bullish.

"We love SVU," he told The Hollywood Reporter. "I think we have deal issues to go through, but I think that show's back again for another year, at least."

Much of the series' future hinges on star Mariska Hargitay, the only remaining original castmember. A longtime favorite among fans, the actress' role on the long-running series has become even more important in recent years following the departure of co-lead Christopher Meloni in 2011. Since then, Hargitay has taken on multiple roles behind-the-scenes, moving up from producer to now executive producer as of the season 18 premiere. She also has directed multiple episodes, including the 400th episode.

Signing a new one-year deal with Hargitay would be a large factor in a potential season 19 renewal, but again Greenblatt said the network would follow her lead as far as she how long she envisions remaining on the series.

Showrunner Rick Eid also recently told THR he's confident about the future. "I'd like to think we have a season 19, a season 20 and a season 21, but that's [the network's] decision," he said. "But I think we're cautiously optimistic there will be more episodes of Law & Order: SVU."

The discussions about SVU's future also happen to coincide with rumblings of a potential spinoff. "We've had some conversations about it, but they've been on-again, off-again, on-again, off-again. I think it's sort of off-again just for the moment because of [the Menendez brothers project], which Dick is very, very involved in," Greenblatt said, pointing to Wolf's Law & Order: True Crime anthology series.

The exec went onto stress that the "slow-going" process of plotting a potential offshoot would likely bleed into next season. "That will happen in its time and could be a planted spinoff of SVU," Greenblatt added. "I don't think it will be this season."

No matter how much longer SVU might run, there's also the question of whether the final season will be announced in advance so that the writers and executive producers have time to plot a final arc for Hargitay's character, NYPD Special Victims Unit's Olivia Benson, and the rest of the squad. Law & Order famously received no such warning — it was axed after it had already shot what would become its series finale — but NBC has made a concerted effort to give viewers, and creatives, time to anticipate final seasons in recent years (see: Parenthood, Parks and Recreation, The Office, 30 Rock).

When asked if the network will know ahead of time about a final season, Greenblatt was optimistic. "I think we will, but you know what? This show just keeps reinventing itself in little ways," he said. "The final season may outlive me. It may not be my decision to ultimately make."

Law & Order: SVU airs Wednesdays at 9 p.m. ET/PT on NBC.

(Additional reporting by Lesley Goldberg)