While it would help I don't think it should take any big changes in technology for a better cigalike but there are a few things going on.
One is the demand structure. Those wanting the smallest devices are a subset of vapors in general. Then those that are wanting the smallest devices themselves will want the focus to be in different places.
You have the new vapor and many of those will be unhappy with the battery life, juice, capacity, or performance. Some of these will move to larger devices. A small subset of another group will be a handful of people how have large devices and might want something more portable or a viable hands free device for short term use. I am sure there are other groups as well but I think all of them will be a minority out here.
You can tell somethings about some of the members by responses to people wanting a better cigalike. Some will instantly suggest a a larger device but that does not help a small minority of us that have something like two or three large devices on their desk as well as twenty eGo's. This tells me quickly I am from a subset of a smaller group.
Of course changes in technology will make the small device better but I think most of the things are in place to have a better cigalike right now.
If you want the smallest that is viable of course compromizes have to be made.
1. There is juice capacity.
2. We have battery capacity. (if the goal is to stay small I don't think having a battery that runs longer than the juice supply is needed)
3. Quality of the vape (this can be different for different people).
While I normally use higher voltage than 3.7v I can deal with. While I don't know all the regulation schemes currently exist out there in existing cigalike batteries I think it is worth finding out. It would be fantastic if they where a 65mm long 9.5 or narrower buck boost battery in existence.
The quality of cartomizers is all over the place but one that has good flavor potential is important to me. Maybe the ideal cartomizer would be at 1.8 - 2.0 ohms and have 1ml to 1.5ml capacity.
I think a combination of a buck boost regulated 65mm long battery and 1.8 ohm cartomizer with good flavor and 1ml, to 1.5ml capacity would bring up the cigalike to nice levels.
This might already exist, I just don't know yet but I am going to see if I can find it.