It is a lot, but to be a stanley cup contender I think you generally need 4 main pieces with complementary depth which are FAR easier to acquire than your 4 key players.
1 C, 1 D , good to great goalie, all around talent ( either 2 way center, great wing player, another 1 D player)
Flyers have 1 proven : the all round talent winger in Michkov.
Zavragin could be the good to great goalie, but goalies are a crapshoot.
You add Demidov and let him transition to 1C, you're only missing the 1 D.
Luchanko is a nice player....but he could be replaced easily. The Denver Barkeys and Oliver Bonks of the world can be easily acquired down the line. But Demidov?? You need some cojones and/or luck to get him.