I just remember that I read of people having problems to install homebrew on their newer Wiis.
Erm...all wii's are equally hackable, with the exception of the wii mini. But that is because the latter has no SD card; it had nothing to do with the firmware. Of all the released glitches, only the twilight hack and bannerbomb were fixed, but letterbomb was never fixed. My guess is that those people either attempted older guides (letterbomb was released relatively late in the wii's life cycle), or had a wii mini.
That said...it might actually matter. I used to think that when a hack was found, it would work on the (at that time) newest firmware...and would be fixed in a next firmware version (once nintendo had a proper look at that hack)*. However, Crediar corrected me on that, as it turns out that nintendo is already busy fixing potential loopholes between firmware versions.
So my answer to the original question would be: it's certainly possible that wiiu homebrew hacks will only work up to firmware <insert number>. No idea how likely it'll be or whether the wiiu will even be hacked in the first place, but "not upgrading" is a good idea (well...if you can miss on the features an update brings, that is).
*kind of like the trucha bug on the wii caused people to stay on lower firmwares or downgrade certain IOS (or IOS'es...I'm not too familiar with that situation) at a certain point in time
It may sound weird, but one of the main reasons for me to get homebrew is the fact that some Wii games (and WiiU games for that matter) destroy the disc drive! The Call of Duty series is especially known for it. The disc drive works like crazy and eventually it dies.
Yes...that certainly does sound weird. Of course disc drives may get worn out by heavy usage, but I really doubt certain games can destroy a disc drive faster than others (it's just one's and zeroes on that thing that get scanned by a laser...this is kind of like saying my barcode scanner can get destroyed faster if I scan too much mars bars).
For the record: you can buy (nearly?) all games on the eshop as well, rather than having them on disc. That way, you can put it on the (small) hard drive or an external USB-drive and thus save your precious disc drive.