SQL> ed
Wrote file afiedt.buf

  1  with depo as (select 'RUR' curr, date'2020-01-21' term ,  date'2016-08-01' dt,  1.1 rate
  2  from dual union all select 'RUR' curr, date'2020-01-21' term ,  date'2016-08-05' dt,  1.15 rate
  3  from dual union all select 'RUR' curr, date'2020-01-21' term ,  date'2016-08-10' dt,  1.2 rate
  4  from dual union all select 'RUR' curr, date'2020-01-21' term ,  date'2016-09-01' dt,  1.1 rate
  5  from dual union all select 'UAH' curr, date'2020-01-21' term ,  date'2016-09-01' dt,  1.0 rate
  6  from dual
  7  )
  8  select
  9    curr,term,dt dt_from
 10   ,lead(dt-1,1,date '2099-01-01') over (partition by curr,term order by dt) dt_to
 11   ,rate
 12  from depo
 13* order by curr,term,rate
SQL> /

CUR TERM     DT_FROM  DT_TO          RATE
--- -------- -------- -------- ----------
RUR 21.01.20 01.08.16 04.08.16        1,1
RUR 21.01.20 01.09.16 01.01.99        1,1
RUR 21.01.20 05.08.16 09.08.16       1,15
RUR 21.01.20 10.08.16 31.08.16        1,2
UAH 21.01.20 01.09.16 01.01.99          1

...