Saying that long rebuild never lead to good things is dishonest.
I think good models for rebuild are Tampa Bay and Chicago (Long rebuild that can take 4+ years).
The Lighting were dead last in the NHL in 2007-2008 before drafting Stamkos, 29th out of 30 in 2008-2009 before drafting Hedman, 25th out of 30 in 2009-2010 (nothing special happened for them in that draft), then ended up 8th in the league in year 4 (ended up lucky and felt on Kucherov and Palat in 2011). But they got a set back by year 5, ended up 21th on 30 in 2011-2012, they drafted their franchise goaltender in Vasilevskiy in the first round. 28th in year 2012-2013, which allowed them to draft Jonathan Drouin which got them eventually Sergachev.
Year 6 was the turn around, were they finished 8th in the league (but still lucked out on Point in the third round). They never looked back again. But it's only by year 10 that they actually started competing for the cup.
In took them 6 years to build there core, and the three first season they were bottom of the league.
Another long rebuilding success story is Chicago.
2003-2004 they ended up 29th out of 30th and ended up picking Cam Barker at 3 overall. 2005-2006 they finish 28th out of 30 and land Jonathan Toews as their futur captain at 3rd overall. Finishing 26th in 2006-2007, they land Patrick Kane at first overall. Next season, they finish 20th and still misses playoff. It's only by year 5 that they started becoming competitive, after Keith and Seabrook finally developped into solid defenseman. The rest is history (3 Stanley Cups).
The moral of the story is that you need to be patient if you are going to be rebuilding, and elite drafting and development is the key, as always since you need to have your franchise players to have any hope of becoming a team that is competitive for the cup, and not only a bubble team.