4 years would be good, because his next one would take him to the end of his peak years and that's how you want contracts to be.
Agree completely. Next contract extension will be when he's 25/26 and could well be a 4 or 5 year contract that confirm him as a Liverpool player into his early 30's (at least).
Trent has been brilliant for us and is absolutely pivotal to how we play. The back end of the season was recent proof of this. He's one of our most important players and deserves to be a high wage earner in this squad.
New contracts for the likes of TAA, Alisson, Fabinho and Salah/Mane are probably as important factors in our short to mid-term success than transfers (probably more important to be fair).