> what if the new name is composed by just one Kanji?
It will be two existing kanji. That's pretty much a given.
Don't worry about it. These compound characters are compatibility characters for older software, and for use as a compact notation in print (i.e., it is mostly a display issue). Any new code point assigned will not be in use now (U+32FF), so you won't break anything. Your software may display a box with the code point address in it, or just an empty box, instead of a glyph from one of the installed fonts.
If you deal with years written with the era name, you tend to get them written as two characters. This year (until the abdication) is 平成３１年 (year 31 of Heisei).
Abbreviations do occur; you will then get only the first character of the name era, so 平３１. This is why the new name will not start with 平, 昭, 大, or 明 (the first characters of the past four era names).
It will be two existing kanji. That's pretty much a given.
Don't worry about it. These compound characters are compatibility characters for older software, and for use as a compact notation in print (i.e., it is mostly a display issue). Any new code point assigned will not be in use now (U+32FF), so you won't break anything. Your software may display a box with the code point address in it, or just an empty box, instead of a glyph from one of the installed fonts.
If you deal with years written with the era name, you tend to get them written as two characters. This year (until the abdication) is 平成３１年 (year 31 of Heisei).
Abbreviations do occur; you will then get only the first character of the name era, so 平３１. This is why the new name will not start with 平, 昭, 大, or 明 (the first characters of the past four era names).