The capabilities of the Taurians are vastly overrated. They gave the SLDF a solid fight a long, long time ago. They had large-scale secret manufacturing assistance from Amaris, a much larger army back then, and a will to fight against what they viewed as Terran oppression. With the Clans? Not so much, as it will take quite some time until they figure out that these are Kerensky's descendants. More importantly, the whole "nuke" card for the Taurians is overplayed. Since the battles against the SLDF, they did not unleash them in any of the intervening conflicts until well into the middle of the Jihad. Most importantly, the modern TDF was beaten handily twice...by a single mercenary unit (the Urukhai and later the Roughriders). The second such merc unit managed to put their entire border defenses in tatters. Personally, I attribute a lot of the overestimation to Periphery 1st edition Syndrome.
Will they give a good hard fight? Yes. Will the Clans see any real need to give the kind of fight the SLDF did, which helped provoke the Taurian insanity response? Nope. Most importantly, as much as the whole "fight to the last man" ideal is given by Taurian fans, I just have trouble accepting it. That's not the reality of planetary populations in canon material, Clan Invasion, or otherwise. There's one specific exception to that, which would be the Taurians versus the SLDF (though a case could be made for the Hegemony worlds resisting Amaris as well). Those are definitely the exceptions, and not the rules. The Taurian people did not react that way ever again, not versus the FedSuns, the Magistracy, or even their own citizens when the nation split. And really, if the nukes do come out, particularly against a staunchly Crusader Clan? Bye-bye Taurus. Welcome to the nightmare of facing real space fleets when you don't have one any more. It's a great scenario, no doubt about it, and it would truly put the Clan philosophy to the test much earlier. But I still can't imagine it as anything but a really costly loss for the TDF.
Edit: All of the above is predicated on hewing close to canon. If you're not, well, it's a whole other ball game. More believable production numbers, using planetary populations to their maximum (meaning continued guerrilla warfare on the ground), and Taurian rage in full effect? Yeah...ouch to the Clans.
Side note: I'm not sure that I would agree with the Outworlds even resorting to nukes. If they did, I could only see them in space. They have gone out of their way to have "clean" warfare throughout their history, and a number of their worlds are agrarian worlds with a great deal of cultural/environmental protection laws in place. It would take a big change in personality for them, as they didn't even use such tactics against the incredibly awful Kuritan invasion forces. And anybody in with 20th century tech can have them. They're crazy easy to make with BT's tech. That they aren't used more often is probably a really good thing.
