Root.ts2

page = Page

page.head {
  stylesheets = TYPO3.TypoScript:Template
	stylesheets {
		templatePath = 'resource://[...]/Private/Templates/Page/Default.html'
		sectionName = 'stylesheets'
	}

	scripts = TYPO3.TypoScript:Template
	scripts {
		templatePath = 'resource://[...]/Private/Templates/Page/Default.html'
		sectionName = 'scripts'
	}
}

page.body {
	templatePath = 'resource://[...]/Private/Templates/Page/Default.html'
	sectionName = 'body'
	parts {
		menu = Menu
		menu.entryLevel = 2
	}
		// These are your content areas, you can define as many as you want, just name them and the nodePath.
	content {
		main = ContentCollection
		main.nodePath = 'main'
	}
}

# Alternative template
pageAlternative < page {
	bodyAttributes.class = 'home'
}

root.pageAlternativeCase {
	condition =  ${q(node).property('name') == 'homepage'}
	renderPath = '/pageAlternative'
}

Solution:

# Alternative template
pageAlternative < page {
    bodyAttributes.class = 'home'
}

root.pageAlternativeCase {
    condition =  ${node.name == 'homepage'}
    renderPath = '/pageAlternative'
}