Yes, that's right. I did a bit of digging, discovered that the 128GB MicroSD memory cards are functionally identical to the 64GB MicroSD memory cards, just with more memory. They are also down to $45 on Amazon for a Sandisk Ultra MicroSDXC card. (Note: if you decide to buy one and use this link I might earn a bit of a commission).
Decided I'd give it a shot. Samsung tells me that my phone is capable of handling memory cards up to 64GB, but when they built this phone, that was the biggest option available. Unfortunately I have about 75GB of music on my itunes and ipod. I've actually gotten to the point on my ipod where every time I get new music I have to go through and delete something that I think I might not want to listen to. It's getting harder and harder to make room as I run out of music that I am willing to let go. I've debated buying a 160GB ipod but they aren't cheap.
As far as music on my phone I picked up an app called iSyncr, created a playlist in iTunes with about 55GB worth of music, and synced that music with the phone. More problems. First of all I had to go through all my music picking which to add to the phone. That took a while. Second my phone fills up with unlistened to podcasts and I run out of memory on the SD card for things like taking pictures. That's a problem. Third, every time I get some new music I want to add to my phone I have to delete something from it and I've already done a serious cull just to get down to 55GB (see above about my music collection problems.
Shut off the phone and removed the old card. Stuck it into my computer's card reader and copied the whole thing over to a new folder on my desktop (can't be too careful). That took about five minutes. Put the new card into the phone, went to the Settings/Storage and voila, showing 119GB available (Side note: I'm always a bit disgusted by how much memory you actually get available versus how big the cards are supposed to be. I don't understand why 9GB is already used up when I haven't put anything on it yet. There's probably a rational explanation and maybe I'll search for that later.) Just to be safe, I formatted the card anyway using the phone, took a couple minutes (Yes, erase all data, since there's not actually anything on it to lost) and I now have enough memory in my phone to store all my music, all my podcasts, and any pictures I take.
Last step, copy all the old data from the computer to the new SD card and reinsert into phone.
OK, so some corrections. Copying everything from the old disk to the computer didn't take about five minutes. For some reason it didn't copy the picture or music folders, so I had to restart that. It claims now that it will take about 40 minutes. No problem, we're talking almost 60GB of data. The music will eventually all be replaced when I resync using iSyncr, but that takes some time so I'll probably set it to go overnight before I go to sleep tonight.
So, in conclusion (you can't tell that it's eight hours later and I am back at my computer, can you?) it worked.
ASIDE [Oh, and to quote the late great Roman Troy Moroni, "you fargin sneaky bastages". A variety of reasons for the lack of usable space. Turns out that HD companies define a GB at 1000MB, where as it's really 1024MB. So a 128GB card has 128,000 bytes but that's really only 125GB. That's a part of it. Apparently the rest of it has to do with creating the partitions that your data uses. Either way it seems a bit sneaky and annoying]
The takeaway, however, is that you can put a 128GB card in your 64GB rated phone (although you will only get 119GB usable memory). Right now I am updating my WHOLE music collection onto my new storage card (except for the part that I took out of iTunes to make it fit on my iPod. That will have to wait.)