I'm actually not too worried (about that part, anyway; I have different concerns about Reforged). The way that SC:R broke some old SC1/BW custom maps was a pretty specific edge case that shouldn't recur on a similar scale with the new and enhanced WC3 WorldEdit. Mainly, as a customs player, the main thing I'd be worried about is the existing bugginess of a lot of classic maps; every customs player remembers what it was like to have a desync or server split where suddenly half the players drop out at once. It's to our benefit that WC3 maps are easy to fix and republish in a format that isn't locked to editing (without some hackiness, anyway); yes, that's how we had all the version control problems that gave us hundreds of competing fan edits of Wintermaul, but it's also what will rescue a lot of the old designs as needed. On the editor's side, SC2 made a gigantic mistake with the region-locking and encrypted publishing that were all intended to give original map creators full control (and possible monetization, they thought) but just ended up annoying everybody at once.
As for Battle.net, integration with their current services is a major positive reason for picking up Reforged at all, and systems for matchmaking or automated tournaments are already in the game; it's not an SC:R situation where we still don't have a 2v2 queue because it never existed in the first place and has to be built from scratch.
Loving these posts man.
The problem is that Warcraft 3 Reforged seems to be a more impactful remaster than SC:R. They are changing a lot of things, from the World Editor, the UI, the online infrastructure to a complete graphical overhaul. This is the reason why Warcraft 3 won't have a 'switch button' like SC:R did. You will be able to switch to the classic or new graphics in the settings menu, but it won't be as simple and fluent as in SC:R.
I'm really worried that they will destroy existing communities, maps and activity with the update. Currently the game has a healthy playerbase, you find games within seconds and a lot of custom maps are still being played. If they break things, that may never come back.
Like, Warcraft 3 has in my opinion always offered a better multiplayer experience than StarCraft II did. Sure, SCII was more modern and had more options. But Warcraft 3 felt like a community. Limited channel sizes, limited friendlists and the ICQ-style chatrooms made it so chatrooms felt cozy and welcoming. Clans really mattered in Warcraft 3, while in SCII it didn't as much.
The custom game mechanics in StarCraft II were problematic for me too:
1. The game list didn't empower smaller map creators. It made sure all the big games kept being hosted on and on and on.
2. The map editor from SCII was brilliant. But also brilliantly complicated. This made sure that people had to be very good at map making to get a simple map up and running. While in Warcraft 3 a complete noob in map making can build a map in a couple of hours.
Now don't get me wrong, I'm really excited for Warcraft 3 Reforged. I dig the new artstyle and I hope it will give the game a new life. But most of my current friends who are playing Warcraft 3 aren't planning to buy reforged.