Well, everything is possible with the right amount of disambiguation rules. Perl 6 doesn't have barewords, and type names must be predeclared. If a subroutine of name x and another symbol with that name (type name, constant, enum element) are in scope, the parser disambiguates in favor of the latter, unless there are parens after the token.
In fact, constants can give you a taste of sigil-less Perl 6 already:
constant x = 4;
say x x x # produces 4444
This works today in both Rakudo and Niecza.