Would an offensive by Hezbollah be able to accomplish anything aside from more terror? I don't think the US (or other Western allies) would allow Israel to be occupied, so they would take action themselves, if the Israeli military were to get into a situation they couldn't fix themselves.
Hezbollah have more capabilities than any other military in the middle east, including some that Israel don't have. I'm not sure they have the ability to defeat Israel, but they have the ability to make Israel fight an exceedingly brutal war. There are currently a lot of experienced people who won't go back to Israel and fight because they don't agree with the government, and because they don't agree with this offensive. If it becomes truly existential to the state, you'll see many many more join up, as well as units like the Georgian Legion etc coming to fight, and they will dial up the brutality to whatever is needed.
You may think they're credible, but they don't know any more than anyone else given that the Israelis are themselves making it all up as they go. We are all in uncharted territory here.
I thought we were discussing the origin of the Hamas attacks, whether Iran sponsored them directly and are directing them, and the likelyhood of a planned escalation in a multi-pronged attack by Hezbollah entering the conflict. US intelligence itself believes that Iran are surprised by the attack, and there would be no military justification for holding back Hezbollah. You'd need to have a reason why Hezbollah waiting to attack [for Israels troops to be committed in Gaza] would be rational.
They've waited for them to setup supply chains, for the US to have a CSG and CAG groups in the region, and for the Iron dome to be fully replenished and preloaded with extra ammo. It's only 200km from Gaza to lebanon; you're talking a maximum of 6-8 hours to move heavy armour and artillery, whilst the IAF and Delilah/PH would have instant range, as well as their own naval assets. Hezbollahs biggest asset is their huge array of rockets. Based on what I've read, listened to, and briefed I don't think it's rational. And I do think that analysts are equipped to answer those sort of questions. (I respect your position to think differently; some still do, though not the US government)
ps. I also think some US direct action is possible if they can coordinate with Israel under article 50. I'm not sure its worth its own post at this point, but they seem postured to do so, or at least have the capability.