If anyone is curious how long this rebuild may last based on previous full-scale, blow-it-up rebuilds, I've compiled a list and sorted the teams by the length it took them to make it back to the post-season, and I've listed their picks during the rebuilding phase.
Oilers - 11YRs to get back to the playoffs
2007 (6th): Gagner
2008 (12th): Went to Ducks in Penner offersheet
2009 (10th): Paajarvi
2010 (1st): Hall
2011 (1st): Nugent-Hopkins
2012 (1st): Yakupov
2013 (7th): Nurse
2014 (3rd): Draisaitl
2015 (1st): McDavid
2016 (4th): Puljujarvi
Leafs - 10YRs to get back to playoffs (excluding 2013 shortened season)
2006 (13th): Tlusty
2007 (13th): Traded to Sharks for Toskala
2008 (5th): Schenn
2009 (7th): Kadri
2010 (2nd): Traded to Bruins for Kessel
2011 (8th): Traded to Bruins for Kessel
2012 (5th): Rielly
2014 (8th): Nylander
2015 (4th): Marner
2016 (1st): Matthews
Sabres - 8YRs to get back to the playoffs
2012 (12th): Grigorenko
2013 (8th): Ristolainen
2014 (2nd): Reinhart
2015 (2nd): Eichel
2016 (8th): Nylander
2017 (8th): Mittelstadt
2018 (1st): Dahlin
2019 (7th): Cozens
Kings - 7YRs to make it back to the playoffs
2003 (13th): Brown
2004 (11th): Tukonen
2005 (11th*): Kopitar
2006 (11th): Bernier
2007 (4th): Hickey
2008 (2nd): Doughty
2009 (5th): Schenn
Islanders - 6YRs to make it back to the playoffs (again, excluding 2013)
2008 (9th): Bailey
2009 (1st): Tavares
2010 (5th): Niederreiter
2011 (5th): Strome
2012 (4th): Reinhart
2014 (5th): Dal Colle
Blackhawks - 5YRs to make it back to the playoffs
2003 (14th): Seabrook
2004 (3rd): Barker
2005 (7th*): Skille
2006 (3rd): Toews
2007 (1st): Kane
2008: (11th): Beach
Pittsburgh - 4YRs to make it back to the playoffs
2002 (5th): Whitney
2003 (1st): Fleury
2004 (2nd): Malkin
2005 (1st*): Crosby
2006 (2nd): Staal
Capitals - 4YRs to make it back to the playoffs
2004 (1st): Ovechkin
2005 (14th*): Pokulok
2006 (4th): Backstrom
2007 (5th): Alzner
Lightning - 3YRs to make it back to the playoffs
2008 (1st): Stamkos
2009 (2nd): Hedman
2010 (6th): Connolly
*lock-out year
Then there are teams like the Panthers, Coyotes and Blue Jackets that have been rebuilding for most of their existence, which I didn't include.
My take from this is that if we can manage to get a couple high-end talents over the next 2-3 drafts, we should be well on our way to contending and won't get stuck rebuilding for a decade like the Oilers, Leafs or Sabres. We need to draft a couple future star players like Stamkos+Hedman, Toews+Kane, or Kopitar+Doughty to turn this ship around and quick.
Issue we have that the above teams didn't have is the lottery now not doesn't guarantee a top 3 selection even if we finished last. Our rebuild could be extended if the lottery balls don't bounce the right way. Could also happen if we draft a bust or two, and unfortunately that's proven to be far more likely outside of the top 3 picks than inside of it.
We're already in year 3 of the rebuild, having finished bottom 2 in 2017/18 and 2018/19, but unfortunately we only Tkachuk to show for it after losing the lottery in 2018 and Dorion throwing away our 2019 1st in the disastrous Duchene deal. Getting Lafreniere/Byfield this year would be huge in turning this franchise around.