The Ilyushin IL96 series is outwardly similar to the Ilyushin IL86 as far as fuselage width, shape and the landing gear, but that's about it. Whereas the IL86 was DESIGNED to be broadly equivalent to the Boeing 747 and fell FAR short of expectations, the IL96-300 and IL96M/T more or less meet the requirements for which they were designed. The IL86 did not have high-bypass turbofans; the IL96-300 has them. The IL86 is a medium-range aircraft because of its heaviness and under-powered, thirsty engines; the IL96-300 is capable of long-range, non-stop flights due to increased fuel capacity, modern and efficient engines, and its all-new, super-critical wing, plus decreased weight due to the extensive use of composites in its construction.
The IL96-300 made its debut at the 1988 Paris airshow and entered service with Aeroflot in 1993. The IL96M/T series is a further improvement on the IL96-300 design in terms of powerplants, avionics, fuel capacity, passenger capacity, and range.
The issue of maintenance and spare parts could be a serious one. Being powered by PW engines and using Rockwell avionics allows the IL96M/T to "cross over" in terms of system compatibility with Western aircraft. However, its fbw control systems, hydraulics, landing gear, fuselage construction panels, etc. are all manufactured only in one place - the Voronezh plant Ilyushin. Of course, Airbus has an excellent infrastructure for distribution of parts, as does Boeing. It is not inconceivable that Ilyushin (and Tupolev as well) could develop such a system, should it become necessary. The question is, of course, one of funding, as well as the ability of Ilyushin to respond to urgent calls should, for example, an IL96M landing gear, stabiliser, or other major component be damaged while the aircraft was outside of Russia. In order to attract Western buyers, Ilyushin (and, again, Tupolev) would have to guarantee 100% support of their aircraft, no matter where in the world their customers might be. Could they do it? I don't doubt it, but all of this has yet to come into play as there are no really large orders for Ilyushin aircraft outside of Russia.