I'm still hesitent to say Tsuna's going to be this good permanently, given his track record, but this time does seem to be going above and beyond past times of him growing a pair.
Before he'd usually just get a pair to take out the arc villain and save his friends. Pretty much just before the final battle and just for the final battle with more of a focus on "this guy is bad and I need to man up and kick his ass".
This time it's pretty much the same, but he's also formed a huge alliance with pretty much everyone from the series except Longchamp's family, Lanchia, the 9th's family, and some Future people we haven't seen in the present (Genkishi, chick with the 'fro, snake charmer guy… Melone base mooks in other words). And now he's stood up to Reborn and is quoting/thinking like Giotto. His change this time has a lot more neon signs pointing it out to us, so hopefully Amano's intending it to stick this time and is highlighting the shit out of it because of that. Or it's the final arc so even if there's "epilogue" where he resets to "mafia is scary", Amano wants us to feel this is the final time Tsuna gets to be badass that we see... Hopefully the former though.