Take a good mental snapshot of Boynton Beach because you won’t recognize the city in 10 years. That’s the opinion of political leaders and administrators who are overseeing a transformation designed to reshape the city’s future. If there is a theme to Boynton’s plans, it might be: Out with the old stuff and in with the new shiny projects. Getting pushed out are old buildings along Federal Highway and Boynton Beach Boulevard as well as the city’s reputation as a haven primarily for retirees and snowbirds. Coming in will be Town Square, which will give Boynton its first downtown in decades; and construction of hundreds of apartments and condos that are attracting young professionals looking to start a family and having the effect of changing the city’s demographics.