Yikes. Everything about this is low-key, or maybe not so low-key, one of the worst pieces of Magic news I've heard in the last few months. This will have significant, negative impacts on paper Magic and Modern if it goes through.
On the surface, Wizards probably wants us to believe this incentivizes playing Magic "for fun," moving the GP scene away from regular grinders who play dozens of events in a year to try and qualify for an MC. It also may disrupt the usual pro scene in favor of Arena and local players, who can't afford/attend all the GP that grinders do, but can have comparable success on Arena. In those regards, this might seem like an okay shift that opens up competitive Magic and allows different players with different backgrounds and experiences to make it big.
Under that surface level, however, this news is a nightmare. First of all, this announcement is the classic, archetypal Wizards communication blunder. They're announcing this 24-48 hours before the first GP of the year? With no context, rationale, or explanation about how player points works? This is a major leap backwards in terms of Wizards communication and bodes very poorly for future communication to come in 2020. Second, this is the kind of announcement that disincentivizes a core group of players from regularly attending paper GP. This will result in lower attendance across the board, especially for formats that top players think can't be solved or gamed. This is where we hit the major, negative Modern impact; even at its absolute healthiest, Modern (indeed, most nonrotating formats) are not the preferred choice for pros. Top players would much rather grind out Standard/Limited on Arena, solve those formats, and then jump into two GP in those formats to try and spike a known metagame. This will significantly disadvantage Modern and Pioneer, formats that are much more open and, more importantly, can't be iterated the same way as Arena Standard. When Pioneer comes to Arena, that leaves Modern in an even worse position.
The final reason this announcement is a disaster (final I'm mentioning now; there are probably many more cons) is that it undermines the long-term optics of Grand Prix. Think GP attendance stinks this year and Wizards is shifting more and more towards digital MTG? Wait until 2021 and Wizards reflects on the last year of GP attendance in 2020, finding even lower attendance than before. This is the sort of self-fulfilling announcement that makes GP worse, justifies further reductions in GP, and justifies further shifts to digital MTG away from large paper events. It's like when Wizards embedded MC streams to artificially inflate viewer count, justifying further investment in Arena-based MTG. Of course, Modern, with no current Arena future, is seriously hurt by this shift. Not to mention paper MTG generally.
I don't often play the "right points" game, but I'm going to call it out here. In late 2018 and early 2019, I and a few others predicted Wizards would seriously commit to Arena-based gameplay with Arena MC events and other high-level Arena play. Many dismissed these predictions as alienating of the core paper demographic, logistically difficult, and too radical even for Wizards. Obviously, we saw lots of 2019 Arena play at high levels in a big way that pushed out paper MTG. We're going to see it again in 2020 and worse, we're going to see it at Worlds. Wizards is going to continue this push and announcements like this are part of their long-term arc to significantly reduce paper MTG events in favor of regular Arena esport grind. I predict we get to a point where Magic Fests are relatively rare, multi-format events that Wizards bills as a "community get together." They will happen once every 1-2 months in a few countries, and the idea will be to consolidate all high-level GP paper play to these scarce events. Everything else will ultimately be Arena. We're not there yet but we are absolutely on that arc.
. I originally thought that the London rule definitely was very bad for constructed magic (especially non-rotating or powerful formats) and it needed to go. However, after reading some of your posts I am not as sure as I was. I really like the idea (EDIT-sorry [mention]idSurge[/mention] ), that WOTC should have had a ban in mind for Tron in modern when the rule was implemented rather than just switching. Really only Tron, Neobrand, and some other combo/linear decks really benefited more from the rule, but all decks benefited from the rule at the same time. I originally wanted to go back to the Vancouver mulligan, but with a ban or two maybe the London mulligan rule still creates more real games of magic and could stick around. You have all made me doubt myself 
. I edited my post. I tend to agree that the london mulligan rule disproportionately helps the combo decks that don't interact. It does help the control and midrange decks, but not as much so in the end I think it's better to go back to the Vancouver mulligan. I will admit that I hadn't thought about the ban argument yet though. I also think going back to the Vancouver rule adds a bit more incentive to add deck manipulation to decks like serum visions, once upon a time, etc which I think is a good thing personally. I would love to see an unban of 
