Ok, well even if there was a boot2v5 update (which they just wont bother to try to do since their last attempt was sketchy), so even if they do and they find a way to make bootmii uninstallable (which they almost can not do by the way they have setup boot1 to check for certain boot2's in which blocks (there is the possibility of 3 boot2's in block 1-7 and the purpose for that is for backups in case of corruption like during an update)), then as long as there is a way to run unsigned code, then bushing already have a way of being able to write to the eeprom to be able to make it so we can download boot2 and get bootmii back into it.
No matter what nintendo does, there will always be a way around it, or just not ever upgrade.
Nintendo would have to build the wii software from the ground up again to have a chance of an update to cause it to be unhackable. But for them to take such a huge risk where there is a high chance for a brick to happen would be retarted.
So guess what, their anti-homebrew efforts will never win. The wii is owned and always will be.
TT has so many other exploitable things that they have found, but just have not released it because there was no need to. Might as well keep it all secret until it can be useful. Hence why boot2v4 was able to have bootmii installed on it the day after the 4.2 update came out.