As we all know, the recent RSS change was relatively despised. (RIP RSS. :c) But this is only one of 3 purely offensive bombs that bombers can use for pure DPS/LD defense. But let me ask my fellow bombers (I mean pure, not toothpick-status combos,):
Has bombing become obsolete offensively in lockdown?
Well RSS is basically useless everywhere now; as much as we try to use shard bombs to full effect, it'll never compare to how good RSS was, in either LD or CW.
Ofc, RSS wasn't the only bomb to use in LD (forgive me, but I've been out of it for a while), as I did use other bombs that haven't been changed. Even just going in dropping Nitros everywhere was effective, as not only did it cause damage, but the KB of it would cause problems for the enemy team, too. Vortexes worked nicely as well if you have someone nearby to dish damage while you lock someone down with them and/or hazes. I would say DBB is effective, but in my experience too many folk run around in Skolver for it to be worth it.
Point is, I wouldn't say it's become obsolete just because the best bomb got stolen from us. There's still all the others.