Since WWII Renault has always had the French government as a major shareholder and one of the issues that comes with that is that the Government insist Renault always borrowed from them when they needed investment. Although that sounds good, it actually turned out to be a poor deal as the Government wanted a commercial rate of interest that could have been bettered if the company were allowed to go to the market instead.
With this in mind, the French Gov have consistently put professional business men in charge of various parts of the company, rather than anyone with an automotive leaning. The positive from that is they've always repaid every single loan they've received (unlike all the other French automotive manufacturers that the French gov have bailed out), but the downside is that they've been run by guys who's only interest is the next model at the right cost and price.
Keeping spares for older cars has never been something they've considered important, to such an extent that stocks for older cars have regularly been sent to the crusher rather than spend the money to store it elsewhere...
They have had the odd adventure such as the manufacture of the R5T, Clio V6 and Spider.
But initially their main adventure was Alpine, but it was always a financially restricted operation where the Alpine guys themselves tried to use as much of the money as possible for competition rather than road cars and their development.
But these were all about 'selling cars today' branding.
They've also been poor at keeping their dealer network happy. This was especially the case with the 'fair competition' thing that came in a few years back, which meant manufacturers couldn't legally stop a dealer from selling other manufacturers cars.
Before this came into effect Renaults idea for the UK was to set up their own network (owned at least partially by them) so they started being really arsey with their dealers and really pissed off a few long long time Renault dealerships (some stayed despite being treated so poorly) . Unfortunately for Renault the new operations were crap and most went bust within a few years, so they've had to set up a new network (using Nissan where possible) but these newer dealers don't give a toss about the older stuff.
Add to this the general UK view of "It's only a Renault" and we can see why GTAs (and until recently A310s and A610a) prices have been so low. They have increased but I wouldn't expect much movement for a few years yet, so Renault are unlikely to put much effort into the spare parts whilst others can cover it.
Alpine A110, Renault Safrane 2.5dt, Hudson Kindred Spirit (Renault powered), transAlp (Honda) and Ducati Multistrada