Do you think MLB Kaleid ruby/sapphire will still be good outside of prisma?

They won't be game changing, but it's still a decent arts/buster boost along with increased NP strength. Still great for a respective arts or buster focused servant.

I don't have any buster boosting CEs above 3* rarity, so I'm pretty happy about the Ruby one. I do have some arts options (yet no arts servants other than Chloe), so the Sapphire one isn't as huge of a deal to me, but once it's MLB, it will still be better than my other options currently, so I'm still pretty thankful for it.

theyre hands down better at mlb than their respective attack types 4 star non mlb CEs currently in the game and i assume many people may not have that. even if you have mlb 4 stars theres still the np aspect thats different. it can matter for some characters with mismatched nps and decks like ilya and david. maybe not the absolut best option for them but great compared to things of similar or lower rarity

They’re well worth it, I think. As the other posters have stated, they add a moderate amount of Buster/Arts and NP damage and are worth using in comparison to non-MLB’d 4 star CEs
I don’t think they’ll be priority for those who have a solid Limited Zero Over/Victor of the Moon/Formal Craft/Another Ending/Heaven’s Feel as any of those can either adequately match one of their effects or surpass it by a large margin.

Personally though, I feel it comes down to the player. If you like the CEs and if they work well with your team then that makes them worth using

It helps to have cheaper in terms of party cost high utility CEs. I am playing this event with Iri as my tank. Once I equipped MLB Meat Wars on her, she became far more useful. I don't need extra healing effectiveness at this difficulty level, so Meat Wars it is instead of Gentle Affection.

The 5-star CE is very powerful. I'd roll for that CE. :)