As I understand it, there are no more base salvage drops. If there's any appearing on the market (and I suspect that there is), it comes from players that still have some stored.
The convert option is probably being kept in the game for the indefinite future for those of us who still have base salvage in our inventories. I, personally, still have base storage on all my toons that predated the change in salvage. Since it doesn't take up any "space", and we didn't need it for the base, I've never done anything with it. I doubt I'm the only one. One of these days, I'll have to make a killing on the market! 
Geni
Base salvage do not drop any more.
The only base salvage left, are those which were in place before the change.
It has a value to collectors, and will most likely be expensive if bought at the markets.
As of Issue 13, there is no longer any use for Base Salvage other than the "Convert" option you noticed. The only "reason" we were given for this is that "people were confused when Base Salvage dropped".
When you convert the Base Salvage, it becomes "Brainstorms". Brainstorms then convert to Invention Salvage using the same Inventions Table after a second conversion - a random Common will cost 1 Brainstorm, while either a Tech or Arcane Rare costs 20 Brainstorms.
All crafted items in your base now are made from Invention Salvage. Each item has 3 alternate recipes, one for each tier of Invention Salvage. Empowerment buffs from an Empowerment Station also are made from Invention Salvage (not that many people use them any more).
Here is a good guide to all the changes made to Bases in Issue 13:
http://boards.cityofheroes.com/showthread.php?t=126110
As others have mentioned, before this change was put into place, some people started hoarding Base Salvage to try to get a complete collection of all pieces. If you happen to have one of the super rare items stashed in your base or on a character, it might get a good price at the CH.
Altoholic - but a Blaster at Heart!
Originally Posted by SpyralPegacyon
"You gave us a world where we could fly. I can't thank you enough for that."
This is probably a very old subject to speak about, but I just picked this game up again after better than a year of inactivity. However, I noticed that there are no base salvage drops anymore. Just invention, I've also noticed that there is still a convert option on the invention tables. So where do you get the salvage for that? From the market? If it's there then something in game is still giving it out. Or is it just on a very rare instance that you get a base salvage drop?
Tankers are the greatest in my book