Napoli have secured a group stage spot and Monaco a qualifying spot.
CL seeding as it stands using the highest seeds, but probably not 100% accurate:
Pot 1:
Atletico or Real Madrid (CL winner)
Barcelona
Bayern
Leicester
Juventus
Benfica
PSG
CSKA Moscow
Pot 2:
Real or Atletico Madrid
Dortmund
Arsenal
Emirates Marketing Project*
EL winner (if Sevilla wins. Liverpool are currently just below PSV, but a win would probably see them in pot 3)
Porto*
Napoli
Leverkusen
Pot 3:
Basel
Donetsk*
Tottenham
Olympiakos*
Dinamo Kiev
Lyon
Villarreal*
Ajax*
Pot 4:
PSV
Sporting
Viktoria Plzen*
Club Brugge
Salzburg*
Celtic*
APOEL Nicosia*
Besiktas
The bold ones are guaranteed a place in the group stage.
The ones with an * would have to go through qualifying rounds.
Teams that could/will be involved in the qualifying rounds:
Champions (everyone have to go through at least two qualifying rounds): Olympiakos, Viktoria Plzen, Astra Giurgiu, FC Salzburg, Dinamo Zagreb, APOEL Nicosia, Legia Warzawa, Hapoel Beer Sheva, BATE Borisov, FC København, Celtic, IFK Norrköping, Ludogorets Razgrad, Rosenborg, Crvena Zvezda, Olympia Ljubljana, Garabag Agdam, AS Trencin, Ferencvaros, FK Astana, Dacia Chisinau, Dinamo Tbilisi, SJK Seinäjoki, FH Hafnarfjordur, Zrinjski Mostar, Vardar Skopje, Dundalk, Mladost Podgorica, Skenderbeu, F91 Dudelange, Crusaders Belfast, Zalgiris Vilnius, FK Liepaja, Valletta FC, Flora Tallinn, B36 Torshavn, The New Saints, Alashkert FC, FC Santa Coloma, Tre Penne Galazzano, Lincoln Red Imps
Non-champions (the first five enter at the playoff stage, the rest have to play each other for that privilege): Villarreal, Borussia Mönchengladbach, Emirates Marketing Project, Porto, Roma, Monaco, FC Rostov, Shaktar Donetsk, Ajax, Anderlecht, Young Boys, Fenerbache, Panathinaikos, Sparta Praha, Steaua Bucuresti
Teams with higher coefficient than Tottenham that could still qualify: Sevilla (as EL winners) and Manchester United (at the expense of City if they beat Bournemouth by 19 goals)