Well, I suppose that Fornost Erain and Tharbad would eventually have been rebuilt. I've been thinking now that maybe Aragorn's people left their land between Mitheithel and Bruinen to begin the recolonization. I've also been trying to rationlize how Halbarad's 30 Rangers must have been only a part of their available manpower. Since we know the Rangers had helped search the lands around Rivendell after the Council of Elrond, many of them must have wintered there or in their homes after the Fellowship left. Subsequently, as the winter began to pass, they may have started going out again (this would be in late February, although I think that might still be too cold for much travel). When the messages arrived, Halbarad gathered all that were left and headed south, probably through Eregion and Dunland, to Rohan.

And I figure there were no Rangers around Bree and the Shire when the troubles began later in the year because those who didn't go south were called back to help defend the homelands (and Rivendell) against any Orcish or Trollish intrusions from the mountains. The Beornings were under attack and "the Misty Mountains were crawling like anthills" on February 26 when Frodo sat on Amon Hen and looked at the world while wearing the One Ring.

I would guess that Aragorn's people were indeed more numerous than we have supposed, and that Halbarad's thirty were perhaps a last guard over their refuges, or maybe just close enough to Rivendell that they could quickly assemble and ride south. Gandalf told Butterbur the Rangers returned with him and the Hobbits, though Tolkien doesn't mention them as part of Elrond's party (and it seems to me Aragorn's people would have wanted to attend his wedding). So maybe Annuminas was first settled by Aragorn's people.
------------------
Xenite.Org: Science Fiction and Fantasy