Blizzard opening Diablo 2's code base would improve company public relations while allowing the loyal community to preserve one of the best games on the market. Diablo 2 Resurrected's release provides a unique opportunity to open legacy Diablo 2's code base as Blizzard has implemented a different Bnet thereby eliminating risk of hacks being created for legacy code and capable of interfering with current Resurrected code. Id software set the standard with Doom and Quake code releases, Blizzard as a company would benefit greatly if it kept such high industry standards for the preservation of classics, and these types of PR moves convert to profit long-term.
Blizzard could even rerelease Legacy Diablo 2 (pre Resurrected) on Gog.com similar to how they released Diablo 1, which is currently thriving for it's age due to that release. A move like that from a company such as Blizzard has potential to shake up the industry.

You can sign here if you to are interested in seeing this happen:
https://chng.it/Kn9KrJkxmV

Pointless. They won't care about it anyway. As for "improving public relations" they also don't care xD