Does this do what you expect?

DECLARE @AlterSQL NVARCHAR(MAX) = 'ALTER TABLE ~tablename~ ALTER COLUMN ~columnname~ NVARCHAR(~maxlength~) ~nullstate~;'
  , @SQLCmd  NVARCHAR(MAX)
  , @SQLParm  NVARCHAR(MAX)
  , @TableName ...

And what is the end goal of what you are trying to accomplish?  Is that really that difficult a question to answer?

First, we are volunteers giving of our own time to help.  We can't see what you see nor can we read your mind (even though there are times it seems...

First, this is a huge view.  I would highly recommend commenting the view so that people new to it can understand what is going on in the view, including the...

So, what is the end game for the original table?