Even if Seward was near-death, his murder would still be viewed highly negatively and the killing of not just the President, but two of others of high official would create a much larger shock. Maybe not on the populace as a whole initially, but for the politicians, yes. Hence perhaps the Radical Republicans would push harder and probably purge of any dissent or such in the South.
As for Alaska, it would nto go to Canada. Great Game was still going on so not much love between the British and the Russians. I think it would likely become the "Taiwan" to the USSR's "China", with either the Romanovs being sent there along with monarchists and followers there or if not, probably a new Russia for the Whites to head to after the Russian Civil War.
A second though more unlikely scenario is for it to become a new place for the defeated Chinese nationalists to go if the British convince the USSR to sell the land around this time or does so as part of arrangements near the end of WW2.
As for Alaska, it would nto go to Canada. Great Game was still going on so not much love between the British and the Russians. I think it would likely become the "Taiwan" to the USSR's "China", with either the Romanovs being sent there along with monarchists and followers there or if not, probably a new Russia for the Whites to head to after the Russian Civil War.
A second though more unlikely scenario is for it to become a new place for the defeated Chinese nationalists to go if the British convince the USSR to sell the land around this time or does so as part of arrangements near the end of WW2.