P2TR has not yet been activated in Bitcoin Core
Taproot was added to bitcoin core a long time ago and you can use it in a testing environment such as the new Signet "network".
However, Taproot is not yet activated in Bitcoin.
But the activation of P2TR will not pass this year, likely it will be before November of this year as we quite know miners will support the activation.
I don't think the signalling is started yet so we can't tell how long it would take for it to reach majority support and activate.
I can say multisig wallet has good advantages even over other wallet types because of the private keys that are generated to sign for transactions can be more than one.
This is an advantage only if your design demands it. For example a company that has to have multiple signers with equal control, a 2of3 escrow,... otherwise the complication it adds is a disadvantage for normal usages not to mention that multi-sig transactions are bigger in size (Schnorr solves this but the complication remains).
Even if the offline wallet private key is seen by hackers, it can be used to steal the whole wallet from someone, it can happen to all wallets, but unlike multisig wallets,
If an attacker can gain access to a properly stored keys in a single-sig wallet it is safe to assume they can access all of them in a multi-sig wallet too. And again storing the keys separately and securely adds a lot of complication.
What do you think? Will Taproot activation increases the number of people and organizations that will make use of multisig wallets because of the transaction fee reduction?
Organizations, yes. Regular people, not that much.