Short answer is, yes, there are always aftermarket solutions to every problem. In reality, though, there were so many SLK's and other MB platforms that used these electronics, that I do not see a real problem in sourcing parts to keep the electrics going in these cars for the very long term. Given how well electronics from other MB platforms swap right in (I am using an ECU from a CL55 AMG, and soon a TCU from a SLR), that only increases the opportunities to keep things rolling. Sprinkle in work that folks like @Viper-666 is doing with his Skreemulator, or that @tighed1 does with RCMs, and problematic electronics become a community sourced thing. So, no, I don't see long term support problems with existing electronics, but if there were, then yes, aftermarket solutions do and will continue to exist.