Having given this some thought, I'm still not happy with the choice to re-sign Saros for this type of deal, however, lots of ways this can play out.
I won't go in to all of them, only the couple that I'd hope for at the very least.
As some have said, Saros is your starter for the next 4-5 years, Askarov in Milwaukee this year and then moving up to backup Saros and eventually taking the full-time starting role down the line.
Another option is similar but make it open competition in a year or two and see if Askarov can displace Saros as the starter. If he can, move Saros to a team who needs a goalie, find a back up and you move on to the next phase of development.
Both of these are dependent upon Askarov taking the next steps in his development and Saros not dropping off the cliff or either one suffering a bad injury.
We're better in the long run to have them both in the system so if one does falter, you have the other to fall back on.