Probablemente no sabe quién soy.
He/she probably doesn’t know who I am.Both the present subjunctive and the present indicative are correct with these
expressions, but quizá(s), tal vez and posiblemente are usually found with the
subjunctive, while probablemente is normally followed by the indicative. By and
large however, the use of the indicative seems to be spreading, even among educated
speakers.18.3.3 (p. 92); 48.1.6 (p. 285); 49.1.3 (p. 293)
71.8.3 Present subjunctive
Es probable que Juan lo sepa.
Juan probably knows about it.Puede (ser) que estén durmiendo.
They are probably sleeping.
Constructions such as as the above are always used with a subjunctive verb.48.1.3 (p. 283); 48.1.5 (p. 284)
71.8.4 Future tense
¿Dónde estará Juan Carlos ahora?
I wonder where Juan Carlos is now.
A esta hora ya estarán en Los Angeles.
At this time they must be in Los Angeles.17.5.2 (p. 76); 48.1.10 (p. 287)
Expressing possibility, probability or uncertainty, etc. 71.8