I would call up Nico as soon as he gets healthy again and let him play 2b and lead off... I believe he’s the 2nd basemen and lead off of the future. Guarantee you that he would be more productive than any of the 3 we have currently at second base
Hoerner is no where near ready for the majors. He's only been in pro ball for about a year. That's before you even factor in that he hasn't played baseball in over a month(think it's almost 2) with a wrist fracture. Missing that much time means even if he were ready to play today(he's not) you're looking at probably 2-3 weeks of rehab assignment to get back up to speed. I can safely tell you this isn't going to happen. I would be shocked if they even put him on the 40 man roster before the end of the season.
As for the premise of needing a leadoff hitter, I'm sure they would like to have one but it's not so simple as snapping your fingers and having someone. And one of the reasons you think they need one(namely speed) is irrelevant with Maddon managing because the cubs don't run under Maddon. They were 24th in the majors last year in SB. They are 30th this year. They were 24th in 2017. They were 20th in 2016. They were 9th in 2015 but that seems like and oddity given Rizzo had 17 stolen bases that year. The next 3 years combined he had 19. In other words, they don't run. Plus Schwarber isn't a bad baserunner. I mean clearly he's not a SB threat but fangraphs has his base running as being about league average.
What I'd like to see them do is to swing for the fences on someone for the trade deadline. With the possible exception of a LH reliever, they don't have any glaring holes really IMO for the next few years. And in Happ and Russell they have some what interesting MLB ready players that the cubs probably don't have long term plans on. Just to throw out an example here but the Indians are 10 games back in the central. Would they listen on Lindor given they only have 2.5 years of control and have yet to re-sign him? Anthony Rendon is a FA after this year I believe. Would the nats sell on him given they are 33-38? Something along those lines. Obviously you're not getting either of those two with solely Happ and Russell but as substitutes for top 50 type prospects they aren't terrible replacements especially if you're a team like Cleveland or Washington who may only be selling on 2019 and not on 2020+. Guys who could potentially help next year vs 2-3 years from now will have more value to certain types of teams.