My opinion is, a restauration of the french monarchy past 1883 and Chambord death is very much like an american second civil war, or a successful operation sea mammal (you know).
As for the bourbons - it all boils down to Louis XIV.
His brother gave us the Orleans (still alive and well, in Paris)
his two grandsons resulted in
a) the Louis XV lineage, that went extinct with Chambord, in 1883
b) the spanish bourbons that were installed there in 1700 (Philip V) and are still alive and well.
an amusing (and totally ASB) TL would be a franco-spanish war over a french restauration of the monarchy... where the spanish Bourbons would be the best pretenders (because they are the last direct great grandsons of Louix XIV, better than the Orleans, which stopped at Louis XIII)
Kind of modern-day war of succession as happened frequently in the middle ages and renaissance...