Point of Divergence, Alexander II of Russia survives his assassination or the assassin never strikes, but the Tsar lives for a few more years. What could this do to Russia and the rest of the World?
The much debated question
Firstly he signs into being the variety of decrees relating to reform of the Russian Empire - he intended several commissions to look at how to reform the administration and the creation of some form of Duma -
It is important to remember that Alexander II was still an autocrat and his proposed reforms were not about transforming Russia into a more democratic state but an attempt by an Emperor who decided police repression was not stopping anarchists and revolutionaries and an alternate idea was needed.
Power would still remain with the Emperor - his reforms had they been enacted would perhaps have been similar to those created after the 1905 revolution - but in the 1880s might have been a decent start rather than too little to late.
In other terms - Russia remains strongly allied with Germany and Austria at least until the accession of Wilhelm II in Germany.
In family terms - the impact of his assasination on his son and grandson both of whom vigorously opposed and resented reform is removed - however they in particular Alexander III are still under the influence of those opposed to the Tsar's reformist agenda - if Alexander II lives into the 1890s then it might be too late to turn them back but Alexander III might try to restrict them.
Alexander II relationship with his eldest surviving son and eventual heir was poor in the early 1880s - particular given Alexander and some of his siblings believed Alexander II would make his morganatic wife Empress - it put a strain on the whole dynasty.
The strain of his father's murder and his own reign etc might allow Alexander III a longer life - which might severely limit the ability of Nicholas II to marry Alix of Hesse.
It also means the Romanov family don't quite indulge in as much public misbehaviour which did damage the reputation of the monarchy partially because Alexander II and III were much more able to deal with their immediate family with authority.