At the rate the LOTR 1/6 figures have been released, it's not surprising people don't hold out much hope for ever getting some of the more difficult to produce characters, like Gothmog. Whether Sideshow ever gets far enough along in the line to do some of the more complicated figures could depend on how long their license with New Line continues.
If there are no complications on the horizon, I want to believe they will do Gothmog at some point. Gothmog will not be an easy figure to make, but I believe he can be done, and I hope Sideshow eventually does make him. We need some minions to balance this line. The Star Wars line has done very well with a balance of good and evil characters, and it's time the LOTR line gets some of that energy, too.
But the real problem is with the figures themselves. It goes beyond using the basic human figure bodies. Even the Hobbits required specially designed bodies. Orcs, goblins, and uruks will require something special, too, if they are to be done with as much authenticity as Sideshow has brought with the other characters so far.
Granted, there are many ifs in the equation, but with the Hobbit on the horizon, I think the possibilities are looking much better now, with another surge of interest likely when the movies finally arrive. I personally hope they go all the way with this line, and I'm in it for the long haul. I guess we'll just have to wait and see, tho.