I imagine there would be perhaps tech or technique which you can choose to determine which memories to compress and countless of others techniques like extra storage that you can instantly access, so I don't see all of these as being real arguments why not become immortal. If I have to choose to be dead and memoryless compared to losing some of my memories, but being still alive, why should I choose being dead and memoryless?
And when losing memories you would first just discard some details, like you lose now anyway, but you would start compressing centuries into rough ideas of what happened, it's just the details that would lack a bit.
I don't see it being a problem at all. And if really something happens with the Universe, sure I can die then, but why would I want to die before?
I want to know what happens, what gets discovered, what happens with humanity, how far do we reach in terms of understanding of what is going on in this place. Why are we here. Imagine dying and not even knowing why you were here.