So I crunched some of the top-32 data to analyze the performance of the various archetypes and the performance of specific deck types within each archetype:
(format: deck name / # of occurences / placement - bold denotes top 8 appearence)
Aggro-Control: 14 total
UGR Threshold: 5 (
3, 9, 16, 20, 27)
UGW Threshold: 5 (
2, 15, 18, 21, 22)
UGRW Threshold: 1 (
1)
Rec-Sur: 1 (
4)
UWB Mages!: 1 (11)
The Rock (BG): 1 (24)
Aggro: 9 total
Goblins (mono-R): 2 (13, 23)
Goblins/w: 2 (
6, 30)
Burninator: 2 (14, 31)
Affinity: 2 (10, 28)
San Diego Zoo: 1 (26)
Combo: 8 total
Loam/Confinement: 3 (12, 17, 32)
Aluren: 2 (19, 29)
High Tide: 1 (25)
Salvagers: 1 (
7)
Control: 1 total
Landstill: 1 (
8)
RW Slide: 1 (
5)
No big surprises here. Aggro-control is the most effective archetype in Legacy.
In fact, aggro-control accounts for nearly 50% of the Top-32 decks. Within the archetype, the various blends of Threshold are the premier aggro-control decks. As you can imagine, this tickles me deeply.

We still can't conclusively determine if UWG >< URG (5 vs. 5), but 4c Threshold taking 1st place suggests that combining the two is the way to go.
Goblins is still the dominant aggro deck. (Like I said, no surprises). With mono-R performing appreciably as well as R/w. Burninator also did notably well and anyone interested in pursuing that deck should review that
Top 128 decks for their ideas.
Combo is stronger than many people realize, placing 8 people in the Top 32. Big winners are the new Loam/Confinement deck which is powerful and resilient, as well as Aluren. But Salvagers and Slide were the best peforming combination decks. And High Tide placed only one person in Top 32. Combo will continue to perform well, but faced with a sea of Threshold, only great players will be able to take 1st where maindeck Meddling Magi and loads of counterspell and various other forms of disruption (Pithing Needle, for instance) are the norm.
Landstill is around, placing one person in the Top 8, but that was it. It's still a "Deck to Beat" in the sense that people will play it and you should probably plan for it, but it's certainly not the premier Legacy deck that it used to be (or was assumed to be, to be more precise).
As in Vintage, hybridization is the way to go.
These are just some preliminary findings. And the data available for Lille, compared with GP: Philadelphia, is overwhelming. But someone should wade through it and produce an article for the format.
I nominate Anusien and/or Smennen.
AppendixGrand Prix: Lille; Final Standings (Top 32)
Rank | Name | Country of Origin | Deck
1 Summersberger, Helmut [AUT] - UGRW Threshold
2 Krutil, Daniel [CZE] - UGW Threshold
3 Labarre, Nicolas [FRA] - UGR Threshold
4 Verdiani, Luca * [ITA] - Rec/Sur
5 Brenner, Martin Joh * [DEU] - RW Slide
6 Le Briand, Loïc * [FRA] - Goblins/w
7 Bracht, Maximilian [DEU] - Salvagers
8 Francois, Nicolas * [FRA] - Landstill
9 Rikeit, Alexander * [DEU] - UGR Threshold
10 Siron, Geoffrey [BEL] - Affinity
11 Doco, Geoffrey [FRA] - UWB Aggro-Conrol (Magi!)
12 Nassif, Gabriel [FRA] - Loam/Confinement
13 Gregoir, Christophe [BEL] - Goblins
14 Krings, Stefan * [DEU] - Burninator
15 Mack, Alex [DEU] - UGW Threshold
16 Hoeh, Hans Joachim [DEU] - UGR Threshold
17 Bertrand, Denis * [FRA] - Loam/Confinement
18 Zidek, Arnost [CZE] - UGW Threshold
19 Ranque, Wilfried [FRA] - Aluren
20 Bertaud, Julien [FRA] - UGR Threshold
21 Cools, Pierre [BEL] - UGW Threshold
22 Oomens, Wessel [NLD] - UGW Threshold
23 Marcik, Michal [CZE] - Goblins
24 Da Costa, Tony * [FRA] - GB Rock
25 Lahanas, Nikolaos [GRC] - High Tide
26 Lindgren, Tommi [CHE] - San Diego Zoo
27 Verrier, Diarmuid [IRL] - UGR Threshold
28 Karsten, Frank [NLD] - Affinity
29 Canali, Pierre [FRA] - Aluren
30 Wörner, Jürgen * [DEU] - Goblins
31 Thebault, Raphael * [FRA] - Burninator
32 Ruel, Antoine [FRA] - Loam/Confinement