This. Works in proprietary formats will be lost to time after supporting vendors lose in the marketplace.

At best, there will be crippled, lossy exports -- lossy because vendors chasing lock-in and network effects don't want to make it easy for customers to leave.

I've cited the demise of Opcode and Studio Vision in the past when making this argument, but that's niche. The Death of Flash brings down the point with greater weight.