This shows the production figures from 1973 to 2014 (sorry I haven't checked them for accuracy) and it makes quire interesting reading.
http://raycee1234.blogspot.co.uk/2015/07/lotus-production-by-model-1980-2014.html
The Elise seems to be by far the top-seller but was certainly on a sales decline - perhaps a 're-launch' as a new Elan would see the return to more significant sales?
I'm probably going to be blasted for this - but if they could invest in a new Elan, and make it scaleable so you could get a 2 seater and a +2 version version, suitable for getting a teenager in the back, as well - and could get it priced from about £40-45k, I'd buy one tomorrow. If this (the 2 variants) could be done (and yes, I accept its a big IF) then that would surely help with the sales to development costs ratio?
I'm sure I'm not the only person in the world who commutes on public transport during the week but needs a car for going out as a family but doesn't need a lot of space. My current car that I bought new in November 2011 has only done 10k miles - so there's no-way I would consider getting 2 cars (my wife dosen't drive).