I get what you're saying, and I mostly agree with it, but I don't think "hopeless" is quite the word for it, and is probably at least partially why Tolkien axed the Noldorian titles. As you mentioned, Tolkien had two different concepts of "hope": estel and amdir.
Amdir is practical hope. It's saying, "ok, we do this, that, and the other thing and we'll probably be ok." It's the strategizing, action-oriented, mindset that most modern folk would think of when they hear "hope". Boromir was very much a man of amdir. Amdir is why he was a good general, why he jumped to plow snow with nothing but his arms on Caradhras with Aragorn so they could all make it back down the mountain. Amdir is good, but it is also fallible.
Estel is... not that. Estel is what Tolkien called "high hope", the enduring hope that the world will turn out right in the end, regardless of what that means for you personally. Estel is saying "I will do what should be done, what must be done, even if it kills me." I guess the closest word would be "faith", but I hesitate to call it that, given the extremely religious connotations that word can have, and, as devout as Tolkien was, he didn't really use estel quite like that. Estel was not a thing that required belief in, or even knowledge of, IlĂșvatar or anything like that.
Frodo and Sam are running on pure estel by the end of RotK. Well, everyone left of the broken Fellowship is by that point, tbh. So you could say that their hope for their own personal selves was gone out the window by that point but that's not quite the same thing as being hopeless.
Sam even has a moment after ditching his pots of his own estel and fallen amdir arguing with each other:
He could not sleep and he held a debate with himself. âWell, come now, weâve done better than you hoped,â he said sturdily. âBegan well anyway. I reckon we crossed half the distance before we stopped. One more day will do it.â And then he paused.
âDonât be a fool, Sam Gamgee,â came an answer in his own voice. âHe wonât go another day like that, if he moves at all. And you canât go on much longer giving him all the water and most of the food.â
âI can go on a good way though, and I will.â
âTo the Mountain, of course.â
âBut what then, Sam Gamgee, what then? When you get there, what are you going to do? He wonât be able to do anything for himself.â
To his dismay Sam realized that he had not got an answer to this. He had no clear idea at all. Frodo had not spoken much to him of his errand, and Sam only knew vaguely that the Ring had somehow to be put into the fire. âThe Cracks of Doom,â he muttered, the old name rising to his mind. âWell, if Master knows how to find them, I donât.â
âThere you are!â came the answer. âItâs all quite useless. He said so himself. You are the fool, going on hoping and toiling. You could have lain down and gone to sleep together days ago, if you hadnât been so dogged. But youâll die just the same, or worse. You might just as well lie down now and give it up. Youâll never get to the top anyway.â
âIâll get there, if I leave everything but my bones behind,â said Sam. âAnd Iâll carry Mr. Frodo up myself, if it breaks my back and heart. So stop arguing!â