According to the latest news from Italian media Juve, if Liverpool successfully signs Isak, Newcastle will need to strengthen their center-forward position. Brentford has refused to release Visa, and Leipzig has set the price for Sesko at €80 million. Newcastle plans to sign either Vlahovic or Muani.
It is reported that Isak is determined to leave, as evidenced by his absence from Newcastle's trip to Singapore for the preseason. Liverpool is actively working on player sales, and if they successfully sell Diaz, it will generate transfer funds to focus on signing Isak, who is eager to join Liverpool. If Isak leaves, Newcastle will sign a replacement, with Vlahovic and Muani being important options for the Magpies.
In my personal opinion, although Newcastle has money, signing Vlahovic is unlikely, not due to the transfer fee but because of the salary. Vlahovic's net annual salary at Juventus is as high as €12 million, and with only one year left on his contract, he is unlikely to leave, waiting for next summer's window to sign for free and collect a signing bonus. Muani, on the other hand, is a possibility, with a pre-tax annual salary of €9.09 million, and he has no issues with physical confrontation. However, his output is unstable, but he offers good value for money, and I feel Muani won't be worse than Sesko.