Isn't it really a question of whether any of these products are really the same thing as before anyway, given that so many of the companies and personnel have come and gone and occasionally risen again under the same brand, but little else.
Also, as bikes have changed, so has the product, and the corporations behind them...
SEDIS of France sold their cycle chain line to Fichtel & Sachs GmbH, a subsidiary of Mannesmann GmbH in 1987, to support the Sachs range of bike parts.
What then became Mannesmann-Sachs AG then sold all their bike business (including SEDIS chains and Sachs gears etc) to the aggressively acquisitive SRAM Corporation in November 1997.
SRAM (founded on Gripshift) went on to acquire RockShox (2002), Zipp (2007), Truvativ (2004), Avid (2004) to complete their collection for a groupset...much like Fichtel& Sachs had done 50 years earlier.
The parent companies still exist within the automotive industry:
Mannesmann-Sachs AG subsequently became ZF-Sachs, when it was acquired by the ZF Friedrichafen Group, with
Sachs being their brand for clutches and shock absorbers.
SEDIS are still making chains in France, just not for bikes any more, and are owned by the enormous
Muragappa Group of India, via
TI Industries (who make 4 million bikes per year in India alone).
All the best,