If we are honest the only coin that we know is going to last until 2050 is bitcoin, no other coin comes to my mind when I think about such a long time frame, now there are a few other good coins out there like ethereum, but even ethereum is not a sure thing as a lot could happen during that time, so we must disregard those predictions as what they are, baseless speculations, and ignore them as there is no point in taking those predictions seriously.
How can we be honest if we also don't know what will the future look like? Don't tell me you are different because you won't still be believable. You also look biased there when you say that bitcoin is the only coin that will remain in the long run. What about Ethereum and other top cryptos?
They are strong as well and I think they can be able to run for a long time. What defines a baseless speculation is that you speculate on something without any basis (obviously). One example is already given by the op but for eth? I can't say that since eth is a coin with strong fundamentals. Overall, it is still up to the person if they will take what they hear seriously or not.
Even bitcoin is uncertain when it comes to prediction in 2050, that is too far to predict and without any information to make prediction beyond our belief. Even our selves can't be sure if we'll live to that point, so we shouldn't waste our time making such baseless predictions. I am also a bitcoin lover but I cannot be bitcoin biased in this case. Personally, I would predict bitcoin and eth in the next bull season, focus on the present and prepare for the nearest bull season we have.