Nice! It would definitely ruin the day for people who design their houses for PvP with small openings for ranged combat and open entry ways. It would also force people to be creative with their homes' interior as it should be.
Having private shielded homes doesn't feel like a part of Felucca at all to be honest! You'll just have to use the bank to re-stock and place your loot, too bad. It might also have a positive impact on crafting, if you can only have what your bank holds you will be buying much more often on your Felucca-only character and shops would be constantly busy.
It might also boost a sense of protecting your home, of keeping people out while your friend tries to come in and restock and such scenarios.
Right now I can just jump into my house, Cure/Heal/STR/DEX/Orange Petal/Purple Petal/Enchant Apple and run out again like nothing happened.. not mention escaping an otherwise unavoidable death- which is completely unfair at least in my eyes. If you'd die 100% without a house and your own private Trammel is the only thing protecting you then just DIE to be honest. Oh and right now the house I live in, in Felucca, is a paradise of locked-down Bright Orange Flowers, Trinsic Roses, Kegs upon Kegs of potions, Enchanted Bandage Springs.. You name it. It certainly feels good but it's luxury beyond need for a PvP facet. I'd prefer to lose all that and have more fun.
Who enjoys all the house hiding going on, with people afraid to flag so that they don't lose their homes' security? It only creates a mini-Trammel in Felucca!
Mind you, this all from someone who completely over-did it with house hiding on his stealther and still does it when he wants to **** ganging people off or whatever.
If they could be lured into my house I could take them off one by one if I'm smart, with the shoving and close spaces and doors.
I disagree with the private guards though.
As for any other form of sieges?
Well, until EA finds a way to program destructible objects/environment in UO's code don't get your hopes high.
Think about this too : A toggle allowing you to deem your house destructible?
Then noone would toggle it. Simple. ;P That's the problem with "switches" in games. It's like they are not there and you might as well not add them- they only hinder those that would have said switches turned on, like PvPers and people who want their houses destructible in your example.
Let's face it: Risk in games means potential FUN with increased difficulty and potential DEATH RATE INCREASE, not actual permanent LOSS of anything. The reward is the fun itself. In UO there's more, there's the other guy's insurance. ;P And what does this have to do with sieges? It's the same mentality, if it's a switch(Public/Private house, anyone?) nobody will use it.
A universal solution would have to be found. In insurance's case this universal solution would hurt players without adding FUN.
In sieges, making all houses destructible would add fun and strategy and definitely increase difficulty. I'd go for that.
Anyway the last parts of my post are hypothetical. Sieges won't happen any time soon in UO, although all it would take would be to add HPs to walls or something.