The rinnegan was his power.
I can't think of a reason as to why his own dojustu is gone.
Going by that logic his sharingan should be gone too.
He still has a crazy amount of strong chakra.
Strongest of the uchiha a fact pointed out many times over.
His susanoo is still larger than others not too mention its multiple arms making hand seals a breeze.
Not too mention he has mastered the sharingan and all its secrets to an entire different level.
mADARA IS STILL top tier
what matters most is even though madara is not the most powerful char in series buthe proves byfeats far most efficient to utilies his power, the reason why kishikilled him that way will raised him much more dangerous because he alone himself the only character manages to gained rinnegan z(praising madara by BZ) hehimself get what he wants the key of moon plan is IT... if he already know it from the start, he can attain anything what he wanted just a proved that he wanted peace....Here is my small calculation for power efficiency:
3 eyes jj madara power output over power input(efficiency)= 100 output power then utilized the usage of that power by means of battle tactics /experience/ knowledge/intelligence/smartness that resulted an input power to 100.....
while,
So6p poweroutput =98delivers an input of 90 he still manage to preserve himself in future while the facts that he is dead but deliver that power to sas and nards
While ,
Kaguya power output of 120 output and has no brain without her will BZ of just say 95 input result....
Meaning GOD MADARA BEATS THIS TWO BY EFFICIENCY TO FULLY UTILIZED THEIR POWERS IN COMBAT,,, STILL I AGGRE THAT MADARA HAS UPPERHANDS AND DANGEROUs