It doesn't need a softfork - only if we absolutely need the ability to receive transactions when offline.

Ark requires BIP-118 or BIP-119 covenant primitives to constrain transaction outputs of a spending transaction to make the receiving on the protocol non-interactive. BIP-118 ANYPREVOUTANYSCRIPT can constrain the spending transaction by hardcoding a 65-byte signature and a 33-byte unknown public key type in a script. Alternatively, BIP-119 CTV can directly constrain transaction outputs to a template hash. Other alternatives would be (1) TXHASH, (2) CAT + CSFS + TAGGEDHASH, or (3) XOR + CSFS + TAGGEDHASH combinations.

These covenant primitives can be emulated using n-of-n multisig by compromising on non-interactivity. Recipients must be online to sign from the n-of-n multisig to constrain the spending transaction. This interactive version doesn't require any changes to Bitcoin and, thus, something that can be deployed on Bitcoin today.