Not seeing how Uboats are finished. The only thing i see is the R4 change. Boohoo you lose your free targetlock you still have a buttload of other crap and shenanigans to pull. I havent even seen many of those on uboats anyway because people bank on vaporizing their target anyway so the Tl would be wasted.
The free target lock was what MADE them a pretty big deal. There are a ton of 'cheap torpedo carriers' in the game, even 'cheap torpedo carriers that can equip Deadeye' (or otherwise don't need to worry about being in range of a TL during their movement phase). The problem is cheap torpedoes, fired with 'quality' dice - something usually reserved for higher-skill pilots.
Yeah, this definitely doesn't make them unplayable, but they're not 75-90+ % 4-hit attacks anymore. Protons are still likely 4 hits, Plasmas will average 3 hits. Now, though, bad dice will be bad dice, and they have a chance of wasting a torp shot, just like everybody else.