2.5 yr old female diagnosed with tuberous sclerosis. Her development is severely delayed, will she develop normal in the future? Walk, talk, chew food

Early intervention. The child should be enrolled in an early intervention program. At age 3 she will be eligible for special education services through her local school system. Most children who show severe developmental delays early in life will face developmental challenges in the future. She may develop all the skills you ask about, but her cognitive delay will be her greatest problem.
Variable. The effect of ts varies from patient to patient. There are adults i know who's only symptoms were skin lesions but had college degrees and normal lives. I have followed others who have had increasingly difficult times with seizures and delays.Severe delay by 2.5 is worrisome. I would prepare for a difficult time and get as much information as you can from the tuberous sclerosis alliance.