After reading a review of this ep that mentions a fatality of "someone we've spent some time with," plus the bit in the teaser, I've been really, really damned worried. There are no shots of Becker in any of the stills from upcoming episodes, Ben Miller mentioned a high body count, and Mansfield himself implied that he might not survive.
I'm going to be pissed if they kill him off--especially this soon. Just when he started getting some character.
However, there are many indications that he's not the one.
1. There's a bit up on YT from s5 filming last August with Mansfield and Hannah in it. The costume she's in isn't the one from this episode, plus she's supposed to be back at the ARC the whole time.
2. Mansfield was in Dublin for at least 6 months. They take about 2.5 weeks to film each episode (though it's out of order.) They started shooting mid-March so they would've been done filming 4x04 sometime in May. There's no way he'd still be on set in August if he died in this ep.
3. The episode synopsis for 4x04 mentions a bit at the end of the episode with Jess and Becker. So he at least comes back to the ARC.
4. ITV's in-guide synopsis for 4x05 has Mansfield listed in the credits.
For a moment, I thought it might be Lester on the chopping block, but he's also mentioned at the end of the synopsis, plus there's that bit from the set visit thingy where he's dressing down Matt and Abby (in different costume than this episode) so I think he's fine. For now.
What I DO think is going to happen...
The review mentioned that the death isn't a redshirt, but I do think it's going to be a single-episode character, specifically, one of the kids at the school. Aside from the big deaths (Ryan, Stephen, Leek, Cutter, Christine, Helen, etc.) they've killed off plenty of non-redshirt, short-arc characters: Tom, Valerie, the journos, etc. However, they've never killed off a kid before, and I think they're going to go for it this time. I think it'll be something like if they killed off Taylor at the end of 2x05. I think it's going to be a definite sympathetic character, and someone we really come to like over the course of the episode, and then bang, they're gone.
...I hope I'm right.
*sigh*