*PSA* Wii Redump collector's can now unscrub ISO files. So scrubbed games can now be verified. You can find the program to do this here
Sites going down is something that will NEVER stop happening. Don't believe otherwise for a second.
Most trackers and similar sites to this one I knew are now gone. There were private trackers with more than 10 years of history that vanished over night and no one even knew what happened.
Today it's Nintendo, tomorrow will be Sony and it won't take long before the whole thing is gone FOR GOOD. In fact ever since Megaupload was busted this is a sure thing for all such sites, except The Pirate Bay (and everyone that watched that Kim Dotcom documentary knows these people are capable of doing whatever they can, from buying politicians to monitoring ilegally their targets).
TPB, however, has declined A LOT over the years in terms of stability and organization, so it's dead in this sense.
As for how to do a backup of your roms (and all sorts of contents you have) I strongly recommend against using external hard drives, pendrives or physical media. These will eventually break or get lost (and believe me, this is only a matter of time, no matter how careful you are). Instead use a free Google Drive account, but do not make the links PUBLIC, instead use SEMI-PRIVATE (or private), semi-private means that only you or the person/account you share with know the link, otherwise is 100% hidden and can't be hit with DMCA. Also Google will not monitor your account or delete anything if not downloaded or if you don't log into it after years (some companies make the links expire or delete your account if you don't use it)
Each free Google Drive account gives you 15 GB. And you can create more than one. Just make sure to write the month/year of account creation (it's in the 1st Gmail message) to avoid being locked from it and being asked that question. If you wish to know the link of your contents you can also create a private blog (in blogspot), that only you can access, hidden from search engines. To this date I never lost anything stored in Google servers.
Other companies like Dropbox or the new Mega will eventually close or their services will become worse. Even with Microsoft that happened. Google is the only one that will never die. Also the download speeds are the best.
Wait I heard some games for the Genesis were taken down? I just checked and they seem to still be there? Were they gone before but brought back?