I’m relatively convinced that at this point in time the most likely avenue to pursue for Cata would be modding. Apart from what the devs here have said regarding the complexity of re-mastering Cata without the source code there’s a couple of other facts I’ve found while doing some reaserch on this. Note these numbers are somewhat rough but we’re looking at ballpark numbers here so please forgive the estimations 
Here is the soruce btw: http://steamspy.com/sale/ (Just type in homeworld)
- Total sales for HW has been around 332,781 copies give or take a few thousand.
- 214k of that was before the summer sale
- at least first 100K or so of that we know was preorders(might be higher) was sold at $30
- the next 115K or so was sold at $35 (Current price on steam)
- another 118k or so copies sold at at $14 (the summer sale 60% off)
Taking into account Steam takes I believe 30% of the sale means HW:R has made around 6mill, give or take. How the money is divided up after that is not something that I could find on google (nor did I expect to
)
Now lets assume that Cata would be an ‘expansion’ DLC. What would you expect to pay for this DLC? Well if we look at the price of the game and what it contains (Two campaigns + MP) and the DLC adds a single campaign + Extras for MP then at a first guess I’d go with half the current price or lets say $15 to make it easy. That said it wouldn’t include the original Cata because no source code so that’s a bit of a snag but we’ll overlook that for now.
The number of DLC/Expansion sold per copy of base game sold is…I want to say all over the place but I’d need to do more research. Interestingly the two games I looked at (although as always the numbers are not 100% reliable) had very similar % of base copies sold to expansions sold. Heroes of might and magic 5 for example with a base copies on steam of 250k has 200k of the first expansion owned and 170k of the second expansion. Interestingly Company of Heroes 1 has 2.5mill copies owned with the first expansion at 2mill and the 2nd at 1.8mill (Yes was very surprised at the ‘similarity’ of those numbers lol). That means a very high 80% first expansion coverage.
So a fictional HW Cataclysm Remastered DLC/Expansion would sell around 265k copies of a Cata DLC/Expansion or around 2.79mill in revenue.
Now there’s a lot of online resources regarding game development cost with estimates ranging from 1mill to 50mill. Here’s an example doc I found: http://theesa.ca/wp-content/uploads/2013/10/Essential-Facts-English.pdf
So even with just a few Google searches I can already tell you that developing a Cata DLC/Expansion without the source code, Taking extremely favorable numbers, having to re-do everything from the ground up and to the same quality as the rest of remastered AND without a ‘Cataclysm Classic’ to sweeten the deal looks iffy at best. The bean counters at Gearbox will have a lot more accurate numbers than me of course access to actual development costs etc.
Also, yes I was a bit bored.