It doesn't matter who you put in charge of the national team in Scotland, they're not going to be successful for a number of years. The problem is not in the manager, but in the quality of players they have to choose from.... they simply aren't there.
How can a Scotland manager pick a team of International players and expect them to beat Sweden, when all he has to choose from is a load of Celtic / Rangers reserves, and a bunch of players that play againt Hibs, Hearts, Livingston week in week out?
The problem is at the root, and needs to work it's way through before a Scotland manager can do a good job.
And it doesn't matter if you guy is Scottish, English, African etc., he faces the same problem... there aren't 11 players out there that are good enough to play at an International level and put on a performance... bottom line.