At this time, I am projecting a 54%-46% victory for Remain.
When the referendum started in earnest, about 2-3 months ago, I had my peg at 54-46. That started inching towards 53-47 on May 22nd. On June 18th, I updated to 52-48. However, since then, the polls have swung back, causing me to update to 53-47 on the 19th, and now back to 54-46.
London and Scotland will both vote Remain by healthy margins. Wales and Northern Ireland will vote to remain by smaller margins. Some parts of England will vote to Remain, parts of the southeast, as well as some cities; but many rural areas in England will be swinging towards the Leave side. As a result, many more seats will be pro-Leave then pro-Remain.
Should things go the other way and Remain win, Scotland will likely not quit the UK over it. Scotland is too divided. We can expect something like a 60-40, or even 65-35 split. We'd need at least a 70-30 split before Scotland would consider leaving over it. Remember too that polls show a third of more of SNP voters are Leave voters. We'd need that figure closer to 85% to cause Scotland to leave.
Otherwise it's just a matter of waiting to see what happens next.
EDITED TO ADD
Just a quick note on the murder of MP Cox. I do not believe this will have a massive impact on the result. The largest numbers impact from my perspective is that I'm upping to 54 today and not tomorrow.