Arnor- Designed For Failure?

[Alfirin]

I'd go with the second, since if played correctly it might, theoretically leave Sauron with a Numenor like situation; an Arnor corrupted, under his control, and still pretty unified and undiminished. With that Sauron might actually be able to play on the pride of the Kings of Arnor enough to make them attempt to invade Gondor to try and claim it's throne as well. And if that happened Sauron would benefiet no matter what. If Arnor actually accomplished such a conquest, Sauron would rule all of the West and would have pretty much won everything. If not, the war would have likely weakened Gondor significantly; and Sauron could have simply had the WK sweep down from Angmar with his armies and take over while they were too damaged to put up sufficient resistance. Gondor is stronger than Arnor, and with it's indestrucable city probably always was, but I tend to think Unified Arnor was probably not so weak that an assault by them would be a cakewalk for Gondor to repulse.

[Belegorn]

I'm checking Appendix F and it seems that some of the other men that inhabited Arnor, were the Dunlendings who used to live by the White Mountains north of Dol Amroth, and went north to the southern Misty Mountains and from there to the Barrowdowns. The Men of Bree are their descendants, "but long before these had become subjects of the North Kingdom of Arnor".