All assets between PAH<>KAH
All Polkadot and Kusama assets will flow freely between PAH<>KAH with Asset Hubs: allow Polkadot, Kusama and Ethereum assets across P<>K bridge by acatangiu · Pull Request #421 · polkadot-fellows/runtimes · GitHub - nearing completion, security audit done.
This includes Polakdot USDC and USDT registered as foreign assets on Kusama Asset Hub.
On top of that, Ethereum assets on Polkadot Asset Hub can be bridged over to Kusama Asset Hub, thus giving Kusama access to trustlessly bridged Ethereum assets (coming over Snowbridge).
This will not make it into the impending Runtimes 1.3.0 release, so we’ll have to bring it with a 1.3.1 release afterwards. Guesstimate for that would be end of Sep, or sometime in Oct.
Permissionless lanes between arbitrary parachains
Also nearing completion: [bridges-v2] Permissionless lanes by bkontur · Pull Request #4949 · paritytech/polkadot-sdk · GitHub, pending security audit.
This will be released with the next stable release of Polkadot-SDK estimated for end of October, and should make it onto Polkadot and Kusama runtimes by EOY.