Will Bernie Sanders' write-in votes be broken out from the total scattered write-in votes?
I know that's generally not done, but it is unusual to have a draft write-in winning 5%+ of the vote in a single state.
It depends on the state. Some states only count votes for official write-in candidates. In Texas, the presidential candidate must file, and include the vice-presidential candidate and 38 elector candidates, each of whom must give their consent.
In other states, a party or slate of electors may file, but they require the consent of the presidential candidate.
In California a slate of elector candidates may file, and designate a presidential candidate without his consent, and there is a Sanders write-in slate in California.
In Washington, write-in votes are counted, but they are not tabulated to individual candidates unless it has an impact on an election. This is primarily to check that apparent write-in votes, undervotes, and overvotes are not actually votes for an on-ballot candidate. Washington does permit write-ins for undeclared write-in candidates, as long as the office and candidate are clear. Since there is a space for write-in candidates for each office, a vote for [X] Write-In "Sanders" under presidential candidate would be clear if he had filed in Washington. But there are 1000s of Sanders in this country. Why should it be assumed that it is a vote for some elderly person in a tiny state in New England?
The SOS is not reporting write-ins, but King County has 2.58% and Pierce County 3.09%.